Looking tired as he appeared in court, Najib was charged with three counts of money-laundering over claims he pocketed 42 million ringgit (USD 10.3 million).
He faces up to 15 years in jail for each charge.
These are in addition to the charges he faced last month after he was first arrested -- three for criminal breach of trust and a separate count that he abused his position to take the money.
He faces up to 20 years in jail for each of those charges.
Malaysia's new government is probing allegations that billions of dollars were looted from state fund 1MDB, which was set up by Najib, in a sophisticated fraud.
Allegations of massive corruption were a major factor behind the electoral earthquake in May that toppled Najib's long-ruling coalition and ushered in a reformist alliance headed by his 93-year-old former mentor Mahathir Mohamad.
In a packed Kuala Lumpur courtroom, the three new charges were read out to Najib.
Asked if he understood the charges, Najib responded: "I understand".
His case was being transferred to another court for a plea to be taken.
He previously denied the other four charges against him.
According to an investigation by the Wall Street Journal, about USD 10 million originating from SRC was transferred to Najib's personal bank accounts, a fraction of the hundreds of millions of dollars from 1MDB that was allegedly funnelled to him.
Najib and the fund deny any wrongdoing.
The US Justice Department, which is seeking to recover items allegedly bought with stolen 1MDB cash in America, estimates that USD 4.5 billion in total was looted from 1MDB.
Investigations into 1MDB have been moving swiftly.
Yesterday, a luxury yacht allegedly paid for with money stolen from 1MDB arrived outside Kuala Lumpur after being handed over by Indonesian authorities.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)