"Rosmah will face several charges", the agency said in a statement.
The media reported yesterday that Rosmah had to present herself at the MACC headquarters in Putrajaya this morning to assist the graft busters in their investigations.
The official says Rosmah Mansor was arrested by the anti-graft agency on Wednesday after it questioned her for a third time over alleged theft and money laundering at the fund. She was first summoned by the agency on June 5 and again on September 26, when she was questioned for almost 13 hours.
After the election loss, a stash of cash, jewelry and hundreds of designer handbags worth as much as $273 million was seized from properties linked to the couple in raids around Kuala Lumpur.
Umno Supreme Council member Lokman Noor Adam and supporters of Rosmah Mansor have stationed themselves at the compound of the MACC headquarters here where she is being detained. Najib has said the items were mostly gifts to his family.
In a statement, the MACC said Rosmah's arrest follows the consent for prosecution by the Attorney-General's Chambers (AGC).
Rosmah Mansor, wife of former Malaysian prime minister Najib Razak, arrives at the Malaysian Anti-Corruption Commission (MACC) in Putrajaya on October 3, 2018.
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She said current EU proposals would effectively leave NI in the Custom's Union, unlike other parts of the UK. Forty-eight lawmakers would need to write such letters to trigger a vote of confidence in the leader.
After the arrest, Rosmah's lawyer, Geethan Ram Vincent, told reporters her lawyers had not been informed of the nature of the charges to be filed against her.
"I suppose tomorrow makes for a great picture and media circus", she added in the Instagram post, which has since received more than 1,300 likes in just over an hour.
Her husband Najib has already been hit with numerous charges on criminal breach of trust, power abuse and money laundering of funds related to 1MDB.
Najib has denied any wrongdoing and pledged not guilty to all the charges.
The media today had earlier speculated that Rosmah would be charged on Thursday.
New Prime Minister Mahathir Mohamad reopened investigations into 1MDB that were suppressed under Najib's rule.