GANDHINAGAR , India (AFP) - The United States on Thursday ended a decade-long boycott of Indian opposition leader Narendra Modi over deadly religious riots, as its envoy held talks with the man tipped to be next prime minister.

Ms Nancy Powell, the US ambassador to India, shook hands with Mr Modi who presented her with a bouquet at his official residence in the western state of Gujarat where he is chief minister, before closed-door talks.

The pair held "comprehensive and wide-ranging discussions" in the state capital Gandhinagar, including on economic development, "terrorist groups", India's assistance in Afghanistan and health, Mr Modi's office said.

Mr Modi also raised a recent row over the "ill-treatment" of a New York-based Indian diplomat, whose arrest and strip search sparked fury in India.

The chief minister said that "such irritants" should not happen if the Indo-US relationship were to realise its full potential, according to a statement from his office.

The United States in 2005 refused Mr Modi a visa under a domestic law that bars entry to any foreign official seen as responsible for "severe violations of religious freedom".

Mr Modi, leader of the Hindu nationalist Bharatiya Janata Party, is accused by rights groups of turning a blind eye to riots that killed up to 2,000 people in Gurajat in 2002 when he was chief minister. Most victims were Muslims.

He has denied any wrongdoing and investigations have cleared him of personal blame, although one of his former ministers was jailed for life for instigating the killing of 97 Muslims.

Ms Powell's meeting brings the US in line with European nations and Australia, which have already restored ties with Mr Modi, as opinion polls show him on course to win power at general elections in May.

Ms Powell did not speak to reporters after the almost hour-long meeting.

"This meeting was part of the US mission's outreach to senior leaders of India's major political parties in advance of the upcoming national elections," the US embassy said in a statement.

If elected premier, Mr Modi would be highly unlikely to experience problems with travel to the US, which generally allows visits by leaders of friendly countries.

Mr Modi has sought to portray himself as a business-savvy leader who can revive India's economy and tackle corruption after a decade of rule by the left-leaning Congress party.

US automaker Ford is due to open a plant this year in Gujarat, where Mr Modi is praised for running an efficient, pro-business government, while General Motors already has a facility there.

Strategic analyst Brahma Chellaney said the United States "is trying to show that it is willing to kiss and make up" given the likelihood of Mr Modi ousting Congress.

"Mr Modi is ahead of his political rivals in all the opinion polls, so the US is simply seeking to protect its economic and strategic interests," Mr Chellaney, from the Delhi-based Centre for Policy Research, told AFP.

Ms Powell will also meet the Congress opposition leader in the state parliament, non-governmental groups and US and Indian businesses while in Gujarat. The US embassy statement emphasised that both sides were seeking "a strategic partnership that is broad and deep".

Mr Modi stated the need to "isolate terrorist groups irrespective of their base or victims" and bring those responsible for the Mumbai attacks in 2008 swiftly to justice, his statement said.

They discussed India's efforts to train officials in neighbouring Afghanistan and assist women in rural areas there, it said.

The US and India have built a growing relationship since estrangement in the Cold War, with most US lawmakers supportive of ties with Delhi.

But Mr Modi has faced opposition from left-leaning members of the US Congress active on human rights as well as academics.

An invitation for Mr Modi to speak last year via Skype at the Wharton School of the University of Pennsylvania was withdrawn after student organisers and professors protested against his participation.

The US-India relationship went through one of its worst crises in years at the end of last year when American authorities arrested Indian diplomat Devyani Khobragade on charges of visa fraud involving her domestic servant and lying about how much she paid her.

Indian lawmakers and commentators accused US authorities of humiliating the diplomat through a strip-search.

The row abated a month ago when Ms Khobragade was allowed to return to India just as she was indicted.