His wife, Rosmah Mansor, was also forced to make a statement through her lawyers addressing allegations about her extravagant lifestyle.
Najib will be asked to account for alleged bribes and murdered Mongolian model Shaariibuugiin Altantuya.
The new administration is seeking answer how billions disappeared from 1MDB, which Najib founded and presided over.
On Friday, the police seized 284 boxes of designer handbags and 72 bags of cash, jewellery and watches belonging to Najib and his wife.
Najib’s lawyer, Harpal Singh Grewal, told the media camped outside the former prime minister’s house that the family was “really very unhappy” that police had confiscated clothes and shoes belonging to his children.
“No attempt was made to verify whether these dresses, shoes, baby clothes and all had anything to do with the investigations which are ongoing,” the lawyer said.
The potential reopening of an investigation into the murder 12 years ago of Mongolian Altantuya could involve Najib, who was defence minister at the time.
It is claimed Malaysian government figures took bribes in the 2002 purchase of Scorpene submarines from France.
The submarine manufacturer DCNS is alleged to have paid more than US$134 million in bribes to a shell company linked to Abdul Razak Baginda, a close associate of Najib who handled the US$1.1-billion deal.
Altantuya was Abdul Razak’s mistress and allegedly wanted a percentage of the proceeds for translating during the deal. She was shot dead and her corpse destroyed with plastic explosives near Kuala Lumpur in 2006.
Bukit Gelugor MP Ramkarpal Singh has called for a royal commission to reopen the case.
Two police officers from Najib’s security team were convicted and are on death row, but the question of who ordered them to kill the model has never been answered.
One of the officers, Sirul Azhar Umar, who is seeking asylum in Australia in 2015 and is held in a migration centre, told the Malaysiakini news website that he was ready to reveal who ordered the murder in exchange for his freedom.
“I am willing to assist the new government to tell what actually transpired, provided that the government grants me full pardon,” Sirul reportedly said.
The former offer said the pair were scapegoats for “important people” but their families in Malaysia prevented them from speaking out.
Ramkarpal said Sirul’s call for a pardon was an insult to the victim and should not be entertained.
“There is absolutely no hint of remorse from Sirul in his interview, particularly when the murder was committed in such a heinous manner,” the MP said.
Happier times: Najib Razak and his wife Rosmah during Malaysia Day celebrations at Merdeka Square, Kuala Lumpur. Picture credit: Wikimedia