Mohamed Apandi Ali said a review of evidence compiled by the country's anti-graft agency showed that the money was a "personal donation from the Saudi royal family".

He gave no further details on the source.

Najib, 62, has for months fended off accusations that the huge payment made into his personal bank accounts in 2013 was syphoned off from a now-struggling state-owned company that he had launched.

But until now, the origin of the money has not been specified, other than claims by Najib's government that it came from unnamed Middle Eastern donors.

"I am satisfied that there is no evidence to show that the donation was a form of gratification given corruptly," Apandi, who was installed by Najib after the scandal broke last year, said in a statement.

He added that "no criminal offence has been committed by (Najib)", and that he would instruct the anti-corruption agency to "close" the case.

The fund transfers were revealed last July just as Najib was battling allegations that hundreds of millions of dollars were missing from deals involving the state company, 1Malaysia Development Berhad (1MDB).

Najib, who chairs 1MDB's board of advisers, and the company, strenuously deny wrongdoing.

But the political opposition and even critics within Najib's ruling party have demanded independent investigations, accusing the premier of sabotaging official probes.

Shortly after the fund movements were revealed, Najib provoked fierce criticism by sacking Malaysia's previous attorney general -- who was investigating the matter -- and appointing Apandi, who has ties to the ruling United Malays National Organisation (UMNO).

It comes after three investigation were submitted by Malaysia’s anti-graft agency, Express reported.

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