The leading Malaysian defence lawyer Mr Karpal Singh has castigated the Prime Minister for trying to avoid courtroom cross-examination over an alleged political conspiracy against his sacked deputy, Anwar Ibrahim.

Mr Singh said it was "quite wrong" of Dr Mahathir Mohamad to think he was above the law.

"The Prime Minister has not got the right to decide what questions he answers," Mr Singh said. "The judge decides questions of relevance, not him."

Anwar, who is already serving a six-year prison term for alleged interference in police investigations, is facing a charge of sodomy along with his adopted brother, Sukma Darmawan.

The tussle over attempts to force Dr Mahathir into the witness box is becoming highly politicised, because national elections could be held as early as next month.

Anwar's wife, Dr Wan Azizah Wan Ismail, is leading a new political party which accuses Dr Mahathir's government of corruption and nepotism, as well as abuses of power aimed at crushing dissent.

Last week the judge presiding over Anwar's sodomy case, Justice Arifin Jaka, issued a subpoena for Dr Mahathir to appear in court today.

However, it has not yet been served and the Prime Minister is not expected in court before the middle of next week.

Defence lawyers have claimed that Dr Mahathir conspired with other government leaders and senior officials to have charges laid following Anwar's dismissal in September last year.

Dr Mahathir said publicly on Tuesday that he would appear in court and make himself available for a pre-appearance interview by defence lawyers if "required" to do so.

"Even if they want to interview me, I want to know what questions, whether >they are relevant to sodomy or not," Dr Mahathir said. "I don't think they can summon me on things like conspiracy and arsenic poisoning."  [Claims of an attempt to poison Anwar in jail with arsenic were not substantiated by independent medical tests.]

Mr Singh said yesterday: "What [Dr Mahathir] is doing is quite wrong.

For a start, witnesses are not supposed to be making comments to the press."

Asked if Dr Mahathir would be cross-examined on the conspiracy allegation, Mr Singh said: "Of course, that is part of the defence."

Defence lawyers have already threatened to seek the Prime Minister's arrest if he fails to appear in court.

Government lawyers have indicated they will either raise objections to the Prime Minister appearing at all or seek tight restrictions on what he can be asked.