Deputy Prime Minister Najib Abdul Razak has once again denied any involvement in a high-profile murder case and accused the country's opposition of trying to exploit it.

In an interview published in Singapore's Straits Times today, Najib was asked about the case involving his close associate, political analyst Abdul Razak Baginda, 47.

The analyst is on trial charged with abetting the murder in October last year of Mongolian woman Altantuya Shaariibuu, 28.

"The fact remains that it is purely a private issue, nothing to do with me," the deputy prime minister told Straits Times , repeating previous denials he has made.

He said the opposition "are so desperate to link whatever they can" but that the public would not believe it.

Two police officers from the Special Action Force (UTK), whose duties include guarding prime minister and Najib, are charged with killing Altantuya.

Prosecutors allege Abdul Razak ordered police to kill his former lover after she harassed him for money.

The trial, which entered its seventh week on Monday, is seen by observers as a test of Malaysia's judicial and political integrity.

Fake photograph

In earlier testimony, Burmaa Oyunchimeg, the victim's cousin, testified she had seen a picture of Altantuya having a meal with Abdul Razak and a "Malaysian government official" as well as others.

Burmaa did not identify the official as the deputy prime minister but said Altantuya told her his name was "Najib Razak."

Following the testimony, Tian Chua, information chief with PKR, posted on the Internet a fake photograph depicting Najib with Altantuya.

"It is aimed to push Najib to explain his link in the case," Tian said.

In the Straits Times interview, Najib said Tian had resorted to "underhand politics. I believe in politics you have to stand on some principles."

The Malaysian Communications and Multimedia Commission, which governs the Internet, has said it was probing the photo.

A police detective testified recently at the trial that only bones remained after Altantuya was shot dead and "blasted" in a jungle area southwest of the capital Kuala Lumpur.