Lead defence counsel Christopher Fernando today threatened impeachment proceedings to be initiated against a defence witness for changing his testimony in sacked deputy prime minister Anwar Ibrahim's sodomy trial.

Deputy director of Internal Revenue Department Mohd Zaid Ismail, who was brought in to substantiate Anwar's defence of alibi, could not remember crucial details when questioned by Fernando this morning.

Fernando told the High Court that he had interviewed the witness previously and he was made to understand that he knew all the details of the trip.

Mohd Zaid who had accompanied Anwar to Europe in early 1993 was unable to answer questions on when the trip was made.

"You don't seem to know anything now," Fernando chastised Mohd Zaid.

Judge Arifin Jaka advised Fernando not to quarrel with the witness and said, "I told you to be careful. Don't simply call witnesses who are not helpful. Mampus nanti".

He reminded Fernando that questioning this witness further would be "disastrous" to the defence's case.

"When I interviewed him, the story was different. Now he has changed his story," said Fernando. He requested for a 10-minute break so that he could speak to the witness.

On resumption after the short break, Mohd Zaid told the court that he left together with Anwar to Malaysia from Frankfurt on Feb 13. Earlier, he had told the court that he did not return with Anwar.

One-time heir apparent Anwar is charged together with his adopted brother Sukma Dermawan Sasmitaat Madja for sodomising former driver Azizan Abu Bakar on "one night between January and March 1993 at 7.45pm". Sukma is also charged with abetting and aiding Anwar to sodomise Azizan.

After Mohd Zaid finished his testimony, Anwar's former police escort DSP Zull Aznam told the court that the ex-deputy premier never requested for a meeting with Azizan. He also told the court that the meeting instead was arranged by deputy special branch director Amir Junus and special branch director Mohd Said Awang.

Zull Aznam also told the court he knew of what transpired between Anwar and Azizan. He said Azizan confided in him and told him that "I was promised money. I was forced to lie and had no other choice."

"He looked relieved after confiding in me and said that Ummi Hafilda was responsible for dragging him into the matter," Zull Aznam said. He also added that he is aware of the matters discussed between Anwar and Azizan.

Lead prosecutor Abdul Gani Patail said at the end of today's trial that they might impeach Zull Aznam for making contradictory statements in court. He pointed out that Zull Aznam, in his earlier testimony, said he had no idea as to what transpired between Azizan and his former boss.

Anwar is currently serving a six-year jail term for abusing his political powers while in office. He had repeatedly denied all charges and said they were fabricated by Mahathir's aides to end his political career.