The MACC is expected to detain former Treasury secretary-general Irwan Serigar Abdullah overnight to facilitate its probe into several criminal breach of trust cases, according to sources.

Whereas former premier Najib Abdul Razak, who was also summoned for questioning, left the MACC headquarters in Putrajaya at 5pm.

According to sources, both Irwan and Najib would be charged at the Kuala Lumpur Sessions Court tomorrow.

The charges are related to 1MDB's dealings with the Abu Dhabi wealth fund known as the International Petroleum Investment Company (IPIC), as well as cases related to BR1M and a pension fund.

"Both of them were summoned for questioning over 1MDB's deals with IPIC.

"Besides this, they are also being investigated for criminal breach of trust over alleged misappropriation of government allocations for BR1M and a pension fund,” a source told Malaysiakini.

According to sources, the amount of funds allegedly misappropriated was RM6 billion and was used to settle 1MDB's debts.

Earlier, Najib arrived at the MACC headquarters in a gray Audi Q7 SUV accompanied by an aide while Irwan arrived at 3.25pm in a Perodua Myvi.

This is the third time MACC has summoned Najib for questioning over 1MDB's dealings with IPIC this month.

In previous cases involving SRC International and 1MDB, MACC had detained Najib overnight before charging him in court the next day.

It was reported that Najib would face an additional six charges on Thursday, bringing the total of charges against him to 38.

MACC deputy chief commissioner Azam Baki confirmed that Irwan will be held overnight and be taken to court tomorrow.

[More to follow]