KUALA LUMPUR (REUTERS) - Malaysia's former prime minister Najib Razak, and the former head of Treasury will be charged on Thursday (Oct 25) in connection with several cases of criminal breach of trust involving government funds, the anti-graft agency said.

The charges are the latest in a widening investigation of corruption, launched by Prime Minister Mahathir Mohamad after Najib was ousted in a shock general election upset in May.

Najib and Tan Sri Mohamad Irwan Serigar Abdullah, former Treasury secretary-general, will be brought to a Kuala Lumpur court on Thursday to be charged, the Malaysian Anti-Corruption Commission said in a statement on Wednesday.

Najib is already facing 32 money laundering, graft and breach of trust charges in relation to transactions linked to state fund 1Malaysia Development Berhad (1MDB).

The US authorities allege that about $4.5 billion (S$6.2 billion) was siphoned from the fund, founded by Najib in 2009.