Malaysia's Anti-Corruption Commission has released a series of audio recordings allegedly revealing former Prime Minister Najib Razak seeking help from Abu Dhabi's crown prince and colluding with a former prosecutor to conceal wrongdoings linked to a massive corruption scandal.

The voice clips, released on Wednesday, marked a new blow to Najib who has denied any misdeeds in the multimillion-dollar looting of the 1MDB state fund and is on trial for corruption after losing office in elections in May 2018.

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Commission chief Latheefa Koya said the nine phone conversations, recorded between January and July 2016, revealed a "clear cover-up and criminal conspiracy" by Najib to stifle investigations, fabricate false evidence, and obstruct justice in the 1MDB scandal.

The agency verified the clips were genuine but Latheefa declined to say how it obtained them. She said the recordings will be given to police for further action. Najib rejected the allegations.

In a July 26, 2016, conversation, Najib purportedly called Abu Dhabi's Crown Prince Mohammed bin Zayed to seek an urgent meeting to resolve an "impasse" over a payment between 1MDB and Abu Dhabi's International Petroleum Investment Co.

That came just days after the US Department of Justice said at least $3.5bn had been misappropriated from the fund by people close to Najib and filed lawsuits to seize allegedly ill-gotten assets linked to 1MDB.

Najib also allegedly asked Prince Mohammed to forge a loan agreement to help his stepson and Hollywood producer Riza Aziz, who was named in the US lawsuit.

Najib said a loan agreement would show the 1MDB money to Riza's production firm Red Granite came from a "legitimate" source.

"I also have this personal request, your highness, that that relates to Riza, my son, and his movie," Najib said on the recording, adding he wants to "have a loan agreement signed to show it is a legitimate financing package … not money-laundering."

"I need that agreement to be sorted out quickly, your highness, that's my special request," said Najib.

"Mr prime minister believe me I want to finish this, this is bad," responded the person on the other line, believed to be Prince Mohammed, according to the phone recordings.

Najib added: "At the moment he's under a bit of pressure in America, I'm worried about him in case they make him a scapegoat. He's totally innocent, all he wanted was to make movies."

Red Granite - which produced the Leonardo DiCaprio film The Wolf of Wall Street - later paid $60m to drop the US lawsuit but Riza was charged in Malaysia last year for money-laundering.

"We can confirm their absolute authenticity," Latheefa said of the recordings. "The contents are shocking; it's a cover-up and subversion of justice."

Najib told reporters he was "shocked by this revelation" and is looking at legal options as the audio clips would have allegedly been recorded while he was the head of government.

"I'm studying the content and I have referred this matter to my lawyers. This has never been done in the history of this country," he said. Najib did not confirm or deny the authenticity of the recordings.

The government communication office of the United Arab Emirates (UAE), the National Media Council, which also represents the palace, did not immediately respond to a request for comment.

Former Malaysian Prime Minister Najib Razak faces dozens of charges over 1MDB, trials are continuing [File: Lim Huey Teng/Reuters]

Najib faces 42 criminal charges in five separate trials related to the alleged theft of billions of dollars from 1MDB, the subject of investigations in at least six countries including the United States, Singapore, and Switzerland. He has pleaded not guilty.

Malaysian and US authorities say about $4.5bn was misappropriated from 1MDB, cofounded by Najib in 2009.

In another recording on January 5, 2016, then-Public Prosecutor Dzulkifli Ahmad allegedly told Najib the 1MDB investigation outcome was detrimental but he and then-Attorney General Apandi Ali could handle the matter on the legal side.

On January 26 that year, Apandi held a news conference to clear Najib of any wrongdoing. Dzulkifli was promoted to anti-corruption agency chief in August 2016.

Latheefa said the agency decided to make the audio recordings public as they were of national interest. She said the release would not be prejudicial to Najib's continuing trials.