Malaysian authorities have filed money laundering charges against a British national who had worked for ex-prime minister Najib Razak as a media adviser, a prosecutor said on Thursday.

The Malaysian government has appointed Singapore law firm Tan Rajah & Cheah to sue 53 individuals and companies to recover funds belonging to tainted state fund 1MDB that have been seized by Singapore.

Najib Razak, the former prime minister of Malaysia, is reportedly instructing a number of high-profile U.S. lawyers as investigations into his alleged involvement in the 1Malaysia Development Bhd (1MDB) scandal intensify, including the law firm helmed by former U.S. Attorney-General John Ashcroft.

1Malaysia Development Berhad (1MDB), the state fund at the heart of the corruption allegations against former prime minister Najib Razak, no longer has legal representation after its law firm relieved itself from acting for the company.

Malaysian Prime Minister Mahathir Mohamad’s new government will review political representation in the country’s largest government-linked investment firms, including the main sovereign and state pension funds, the funds have said.

Mahathir Mohamad, who pulled off a stunning general election win, was not sworn in as the new prime minister of Malaysia on May 10, a spokesman for the King’s palace said, but gave no reason for the change in schedule.