Former prime minister Dr Mahathir Mohamad has criticised the Singapore authorities for not disclosing the names of people involved in the 1MDB scandal.

In an interview with the Financial Times, Mahathir said the country was not "doing the right thing".

"Notice that the government of Singapore is very reluctant to pinpoint the people involved in this corruption.

"It affects Singapore’s reputation as a financial centre. It is not doing the right thing. The people who accepted the bribes are not the people who are laundering the money," Mahathir was quoted as saying.

The Monetary Authority of Singapore said it is cooperating with international investigations into the 1MDB scandal but have not named the key players.

However, it has charged one of its citizens, former banker Yeo Jiawei, for facilitating in laundering 1MDB's funds.

At least US$3.5 billion is believed to have been stolen from the Malaysian fund, according to US and Swiss authorities.

The US has moved to confiscate US$1 billion in assets belonging to Penang-born businessman Jho Low, Prime Minister Najib Abdul Razak's stepson Riza Aziz, as well as former United Arab Emirates officials Khadem Al Qubaisi and Mohamed Badawy Al Husseiny.

The court documents also named 'Malaysian Official 1' as a high-ranking official in the Malaysian government who held a position of authority in 1MDB as well.

The US Department of Justice believed that the assets were acquired using money stolen from 1MDB.

Mahathir said the US action had exposed Najib despite attempts to cover up the scandal.

"It is quite obvious that the party (Umno) that is being led by Najib is being used by Najib to cover up," said Mahathir in the interview.

Mahathir vowed that his upcoming new party will be used to oust Najib as prime minister and will work with the opposition for this sole purpose.