The Kuala Lumpur High Court today allowed Prime Minister Najib Abdul Razak's application to intervene in former minister Zaid Ibrahim's lawsuit seeking the disclosure of his bank accounts.

Najib's lawyer Wan Azmir Wan Majid said that Judicial Commissioner Rohani Ismail had ruled that his client has sufficient interest to intervene in the matter.

"Because obviously, it is his bank account," he told reporters after the proceedings held in chambers.

"Since we are now part of the proceedings, we are going to file affidavits in reply to affidavits which have been filed previously," he said, adding that the submissions would be made on Aug 18.

Najib had in December last year applied to intervene in a lawsuit filed by Zaid against AmBank Islamic Berhad.

Zaid had filed the ex-parte application last October to compel AmBank Islamic Berhad to disclose details pertaining to an RM2.6 billion fund believed to have been deposited into five accounts allegedly belonging to Najib.

Zaid's application is also related to his representative action suit filed against Najib, 1MDB, the government, and Najib’s stepson Riza Aziz last August 16.

He claimed in the suit that Najib had breached his fiduciary duty and wants him to return the US$731 million deposited in his private bank accounts.

Zaid's lawyer Americk Sidhu said Najib is now formally involved in discovery proceedings but there is still a long way to go before the main trial will proceed.

"Whether or not the court will allow our application (to disclose the details) is yet to be decided.

"(And) if the application is allowed, the bank can still dispute the order," he said.

He added that the court has set Sept 15 as the next case management date to decide the next course of action.