Malaysia's former auditor-general Ambrin Buang, who was responsible for all government audits, testified in court this week that he was under pressure from top officials to alter the contents of an audit report on 1Malaysia Development Berhad (1MDB) that was to be submitted to a bipartisan parliamentary committee.

The 1MDB audit report that was eventually submitted to Parliament's Public Accounts Committee had 16 pages fewer than its original version, after some parts were erased to mask the severity of the now-defunct state fund's deals in amassing billion-dollar debts, Tan Sri Ambrin told the High Court.

"There was no choice. I was under pressure to do the amendments," he said yesterday, in the third of former prime minister Najib Razak's five trials tied to 1MDB.

Najib is charged with one count of corruption for allegedly ordering the 1MDB audit report to be altered. He is facing the trial jointly with former 1MDB CEO Arul Kanda, with the latter facing one charge for abetting Najib.

Mr Ambrin, 70, testified that alterations were made to 1MDB's audit report in a meeting attended by top officials, including former chief secretary Ali Hamsa and Arul in February 2016.

The case involves four issues raised in the audit report that were eventually removed from its final publication.

A key issue was the two conflicting financial statements for the year 2014, with one statement presented to Companies Commission of Malaysia and another to the finance ministry and two banks.

The other three issues were to strike out a mention that fugitive financier Low Taek Jho was present at a 1MDB board meeting though he held no position in 1MDB; a delay in issuing an Islamic bond; and removing an agreement involving Country Group Securities Thailand and ACME Time.

Low controlled both Country Group and ACME Time.

On Wednesday, Mr Ambrin told the court that he agreed to the audit amendments after being assured by Najib that the authorities would separately investigate the two versions of 1MDB financial statements.

"Najib asked me not to include the issue of the two versions of 1MDB's financial statements in the 1MDB audit report," he said.

"Najib promised me that the authorities will probe. He told me that 'we will get to the bottom of this'," the ex-top auditor added.

But no police report was lodged despite promises made to do so.

During one meeting chaired by Tan Sri Ali that was secretly voice-recorded by an audit department employee, a frustrated-sounding Mr Ambrin raised his voice several times.

Mr Ali then urged Mr Ambrin to keep his emotions in check, saying: "Tan Sri, maybe you should keep your feeling with you, keep your disappointment with you."

The trial will resume on Jan 13.