By Agence France-Presse
Najib, 64, unexpectedly lost a May 9 election to a political coalition that had focused on allegations that he oversaw the looting of billions of dollars from sovereign wealth fund 1MDB in a vast conspiracy of fraud and money-laundering stretching around the world.
Najib was already barred from leaving Malaysia in the wake of the election, and police seized large amounts of cash, jewels and luxury items from his home and other sites last week.
State-run Bernama news agency said Najib had been ordered to appear before the Malaysian Anti-Corruption Commission (MACC) next Tuesday.
"So far, he is asked to turn up next Tuesday to enable us to record his statement relating to SRC International," Bernama quoted an MACC source as saying in the report issued late Friday.
SRC International was a subsidiary of 1MDB before being placed directly under the finance ministry in 2012. Najib was both prime minister and finance minister at the time.
Hundreds of millions of dollars linked to SRC are alleged to have gone missing, in just one component of the wide-ranging 1MDB affair.
As reports proliferated in recent years that billions were looted from 1MDB by Najib, his family and cronies, his government shut down domestic inquiries into the scandal, arrested critics calling for a full investigations and muzzled news organisations reporting on the affair.
But 92-year-old former premier Mahathir Mohamad, expressing disgust over the scandal, came out of retirement to lead a diverse alliance of parties to a stunning electoral victory on May 9.
Mahathir has vowed to fully investigate the 1MDB scandal.