By Agence France-Presse
Allegations that billions of dollars were taken from investment vehicle 1MDB and used to buy everything from a super-yacht to artworks played a major role in prompting voters to oust Najib's long-ruling regime at May elections.
Najib has now been hit with a total of 39 charges since losing power, most related to his alleged role in looting 1MDB.
Other figures linked to the previous administration have also been hauled into court.
The latest charges focus on claims that Najib ordered a report on 1MDB by the government's official audit body to be altered in February 2016, with the help of Arul Kanda, who was president and chief executive of the sovereign wealth fund at the time.
It was then presented to a parliamentary committee.
The government's chief auditor said last month the audit had been changed to remove details about the fund's true financial condition and to erase a mention of Low Taek Jho, a financier accused of masterminding the fraud, at a 1MDB board meeting.
Najib, 65, is accused of breaking laws that forbid officials from using their position for personal gain and faces up to 20 years in jail if convicted.
He pleaded not guilty and has denied all the charges against him so far.
Arul, being charged for the first time over the scandal, is accused of assisting Najib in altering the audit. He denied the allegation, and faces up to 20 years in jail if convicted.
Both suspects were released on bail of 500,000 ringgit ($120,000) each.