The Prime Minister's Office (PMO) has denied claims by Australian newspapers that Prime Minister Najib Abdul Razak had links to a bribery scandal which occured between 1999 and 2004.

However, the PMO did not comment on the main allegation by The Age and Sydney Morning Herald that Malaysian authorities are refusing to cooperate with Australian investigators.

The two newspapers had claimed that the Commonwealth Attorney-General's Department had made a formal mutual assistance request to hand over sensitive information about the financial dealings of a group of Malaysians.

They were described as politically-linked middlemen accused of bribing Malaysian officials to secure contracts for two Australian Reserve Bank companies to print polymer currency notes for Malaysia.

These middlemen were reported to have links with figures in the offices of both Najib, while he was deputy prime minister, and then Prime Minister Abdullah Ahmad Badawi ( photo ).

Putrajaya's reluctance to help, said the newspapers, had hampered efforts by the Commonwealth Director of Public Prosecutions to make its case against former senior executives from the two Reserve Bank firms, who conspired to bribe Malaysian officials.

The PMO described the allegation as a "desperate attempt" to link Najib to the alleged wrongdoings of the said middlemen who may have happened to be in the same room as him at some time or another.

"The article does not contain a single direct allegation about the prime minister – and for good reason.

"There are none to be made and there is not one shred of evidence that the prime minister was in any way involved in the case that the courts have already made judgments on, with individuals convicted and punished.

"Fairfax Media knows this, yet their article persistently attempts to mislead and imply not only that he had some involvement, but that he also might have been a beneficiary of any alleged wrongdoing.

"Instead of providing evidence to link the prime minister to the case, the article relies heavily on a series of slippery, non-conclusive words - 'suspected', 'alleged', 'suggesting' - to lead the reader into thinking that the prime minister is guilty by association," said the PMO.