Former prime minister Najib Abdul Razak has said he would have acted if he knew 1MDB fund were being misappropriated.

In an interview with Reuters, Najib said he had only wanted to do good for the country through the state investment firm.

"I didn't benefit from 1MDB, because I believe that the 1MDB was created to do something good for the country.

"If I knew there was going to be misappropriation of funds, if that was my knowledge, I would have acted," he was quoted as saying.