NEW YORK (NYTIMES) - In the 1970s, long after its encyclopaedic collection had been acknowledged as among the world's finest, The Metropolitan Museum of Art (Met) recognised it had slender holdings in South or South-east Asian art.

An in-house estimate suggested that no more than 60 objects were worth exhibiting.

But over the next two decades, it built a world-class collection, acquiring hundreds of artefacts for new galleries that now occupy the equivalent of more than a city block. The massive undertaking brought the glories of ancient Cambodia as well as India, Thailand and Vietnam to New York, where they took pride of place alongside the Western masterpieces that had long defined the museum.

Significant to this effort was Mr Douglas Latchford, a British-Thai businessman who had become a leading collector, scholar and dealer in Khmer art - and would later be charged with illegal trafficking in Cambodian artefacts.

Starting in 1983, Mr Latchford gave or sold the museum 13 artefacts - a modest amount, but one that included premier examples of Khmer sculpture.

Two gifts were the torsos of massive, twin stone statues, the Kneeling Attendants, that guarded the doorway to Gallery 249, which focused on Khmer art. The wall label noted that they had been given "in honour of Martin Lerner", the curator of South and South-east Asian art who directed the Met's collecting effort.

Cambodian officials now say they believe many of those 13 items were stolen. They suspect dozens of other artefacts in that gallery and others were also looted, often trafficked by Mr Latchford, who died in 2020. They say they believe he often sold stolen items to other donors and dealers before they ended up at the museum.

The Cambodians have enlisted the help of the US Justice Department to press for the return of dozens of artefacts, basing their claim in part on the account of a reformed looter.

The looter, Mr Toek Tik, identified 33 artefacts in the Met collection as objects he recalled personally plundering and selling to intermediaries who often did business with Mr Latchford.

But the dispute has evolved into something of an odd stand-off.

The Met says it has a track record of returning items proven to have been looted, that for years it has been reviewing its Khmer artefacts and that it has updated several provenances as a result and turned that information over to Cambodian officials.

But the Met has refused to show Cambodia a set of internal documents that might buttress - or undermine - the museum's proper title to the objects, whose slim ownership histories are listed on the Met website.

Cambodian officials, meanwhile, have turned evidence of looting over to the federal authorities but not to the museum itself.

The Met said in a statement: "We have not been provided Toek Tik's accounts, nor do we know the identity of the 33 items. We have repeatedly requested any evidence demonstrating works were stolen from Cambodia."

Mr Bradley Gordon, a lawyer for the Cambodian government, responded: "The burden of proof should be on the Met to prove the Met has the right to legally own Cambodia's national treasures."

In pursuing a robust set of claims, Cambodian officials are relying heavily on the recollection of places and events from, in some cases, four decades ago by Mr Toek Tik, who died last year at age 62.

His account was detailed, and the Cambodians say much of it has been corroborated by interviews with fellow thieves and by evidence found at the remote jungle temple sites that were plundered or among Mr Latchford's papers.

But sometimes Mr Toek Tik remembered finding several different objects, all of which he thought roughly resembled an item in the Met.

Cambodian officials say they have also discovered records that raise concerns about how thoroughly Met officials reviewed many of the items before acquiring them. In particular, they cite documents that show that soon after Mr Lerner - the Met curator who led the collecting efforts - stepped down from his post in 2003 to become an art market consultant, his clients included Mr Latchford.

The documents, found on Mr Latchford's computer after it was turned over to Cambodia by his daughter, show that Mr Lerner used his expertise and reputation as a former Met expert to help Mr Latchford market items for sale.

In letters drawn up for Latchford clients, Mr Lerner vouched for the value and significance of artefacts, in one case using language that closely tracked what Mr Latchford had asked him to write. They also owned at least one artefact together.

Mr Lerner, one of the most respected experts in his field, said in an interview that his business relationship with Mr Latchford did not start until after he had left the Met and that he had not known of any taint to the Latchford items he acquired for the museum or later vouched for as a consultant. But he acknowledged that, like other curators at the time, he did not do a lot to investigate where Mr Latchford was securing his artefacts, a position he now regrets.

"Knowing what I know now, I should probably not have worked so closely with Mr Latchford," he said.

Mr Latchford was regarded as a collector and dealer, not a suspected trafficker, during the 31 years Mr Lerner worked at the Met. In 2008, almost five years after Mr Lerner left the museum, Mr Latchford was honoured by the Cambodian government in recognition of his donations to its museums. And the Met has no policy that forbids curators from later serving as private consultants.

But Mr Lerner continued to work with Mr Latchford for years after suspicions about the dealer's conduct became public.

In 2012, federal investigators said the dealer had knowingly purchased a looted antiquity.

In 2013, the Kneeling Attendants that Mr Latchford had given the Met in Mr Lerner's honour were found to have been stolen.

Mr Lerner was still advising Mr Latchford in June 2019, six months before the dealer was charged with trafficking in looted relics and creating false provenance documents to hide his tracks.

The case was withdrawn after the death of Mr Latchford, who long denied any role in trafficking.

The push to recover items from the Met is at the vanguard of an effort by Cambodia to secure the return of hundreds of artefacts it believes were looted during the years of civil war and upheaval that ravaged the country from the 1970s to the late 1990s.

For decades, the Met's stated policy has been for curators to collect additional, available evidence to support the legitimacy and ownership history of artefacts before acquiring them. Cambodian officials requested an opportunity to review those internal records from the Met but were turned down.

"We have not asked the Met to take on any burdensome task," Dr Phoeurng Sackona, Minister of Culture and Fine Arts for Cambodia, said in a statement.

"Rather, we have only requested the precise information and research that the Met declares to the public and in its policies and procedures that it already has obtained on every cultural property from another country before accepting it into the museum."

The Met said it regards such documents as internal business records, not subject to disclosure "without a legal basis".

In 2013, the Met returned the Kneeling Attendants - the massive 10th-century statues that Mr Latchford had donated in Mr Lerner's honour - after evidence surfaced that they were stolen.

Earlier this month, the US Attorney's Office for the Southern District of New York announced the return of 30 looted artefacts that had been sold by Mr Latchford to collectors and to the Denver Art Museum.

Cambodian officials have begun talks with other museums, including the Smithsonian and the Brooklyn Museum, which they say have been more cooperative. But they view the Met negotiations as crucial, they said.

"The Met sets the standards for other museums," said Mr Gordon, the lawyer for the Cambodian government, "so it's important that they are totally transparent."