A former Malaysian law minister has filed a legal suit challenging a decision by the country's attorney general not to prosecute Prime Minister Najib Razak over a financial scandal that involved more than $700 million dollars channeled into his private bank accounts.

Zaid Ibrahim said Tuesday that statements by the anti-corruption agency and other agencies investigating an indebted state investment fund linked to the premier indicated "strong evidence of wrongdoing" by Najib.

He says possible offences included money laundering and criminal breach of trust.

Zaid says Attorney General Mohamed Apandi Ali's decision last week not to prosecute Najib was "unreasonable and constituted an improper exercise of discretion."

Apandi said most of the money was a personal donation from the Saudi royal family and that Najib had returned most of it.