PUTRAJAYA - The anti-graft agency on Wednesday (Jan 8) released voice recordings purportedly of former prime minister Najib Razak conspiring with senior Malaysian officials to cover up the 1MDB scandal, including asking United Arab Emirates leaders to do the same in a dispute over US$6.5 billion (S$8.78 billion) in debt payments to Abu Dhabi's International Petroleum Investment Company (IPIC).

MACC played several clips from 2016 which allegedly showed an attempt to manipulate investigations and other fraudulent acts aimed at concealing missing funds from 1MDB, the state investment firm under the then premier's control.

Najib, whose Barisan Nasional coalition government lost power in the May 2018 election, is facing 42 graft charges related to 1MDB which his legal team has dismissed, claiming that the former premier was a victim of fugitive financier Low Taek Jho who was the central figure in siphoning billions from the state fund.

Low has in turn, denied this claim, insisting that the allegations against him are politically motivated.

MACC chief Latheefa Koya did not reveal the source of the nine recordings - all of which appeared to be phone conversations - but said they were received all at once.

"The recordings show a clear case of abuse of power, conspiracy, fabrication of false evidence and leaking of state secrets," she told a press conference, adding that the material would be shared with other enforcement agencies.

The MACC believes that among the voices on the recordings are Najib's wife Rosmah Mansor (who is facing separate graft charges), former MACC chief Dzulkifli Ahmad and prominent Abu Dhabi figures, including Crown Prince Sheikh Mohammed Zayed Al-Nahyan and the chief executive officer of the emirate's sovereign wealth fund, Mubadala Development Company, Khaldoon Khalifa Al-Mubarak.

In a recording of an alleged conversation on Jan 5, 2016 between Najib and Tan Sri Dzulkifli, the former MACC chief described the situation as "very bad" but told the former premier not to worry as "we can handle this and let Apandi make the decision". The then Attorney General Apandi Ali cleared Najib of wrongdoing later in the same month.

Central to the alleged discussions with Abu Dhabi individuals was the United States' Department of Justice (DoJ) announcement in July 2016 that it was seizing over US$1 billion in assets out of the US$3.5 billion siphoned from 1MDB. The DOJ also also named Najib's stepson Riza Aziz as a "relevant individual" in investigations.

Najib purportedly sought the help of the Crown Prince to arrange a "loan agreement" for Mr Riza to show that it was a "legitimate financing package" and that there was "no money laundering" in funding the latter's filmmaking business which spawned the 2013 movie Wolf of Wall Street.

However, the recordings do not show if the Abu Dhabi figures acceded to these suggestions.

The 1MDB-IPIC dispute largely stemmed from the fact that the Malaysian fund said that it had deposited US$3.5 billion with the Abu Dhabi firm which denied ever receiving the amount.

Another recording allegedly had Rosmah telling Najib "you are the prime minister, you should take charge" to get IPIC to retract its decision to bring 1MDB to arbitration and to "sort out the problem" for her son, Riza.

Najib said he was shocked by the apparent and unprecedented tapping of a sitting prime minister's phone, and the possibility that it was illegal.

"This can affect diplomatic relations and Malaysia's interests with other nations," he told reporters.

He added on Facebook later that "because these recordings help my case, my lawyer wants to ask MACC to hand them over to be used as evidence" if they are proven to be authentic and legal.

Najib's lawyer Shafee Abdullah also said they were contemplating contempt proceedings against the MACC and its chief Latheefa for releasing information that was sub judice - under judicial consideration and prohibited from discussion - under the ongoing 1MDB trials.

Rosmah also did not confirm or deny whether the recording of her discussing the 1MDB situation with her husband was genuine, merely saying that her lawyers will "take care of it".