Passengers on a Malaysian ferry that burst into flames and sank had to leap into the sea to escape the blaze, in an accident that killed four people and injured four more, state news agency Bernama said on Sunday.

At least 100 people were aboard the "Seagull Express", an old and rickety ship that was battling engine problems as it headed for the popular Malaysian resort island of Tioman from Mersing in southern Johor state on Saturday, the agency said.

The fire spread rapidly, filling the passenger cabin with thick smoke within minutes, said passenger Ng Li Peng, 41.

"It was so dark and we were blinded," she said. "I grabbed my two children and hurled them into the sea and both my husband and I jumped into the sea as well."

"We would have perished if we had remained in the ferry. We do not know how to swim but had to jump into the sea as we had no other choice," Ng told Bernama, adding that crew scrambled to save themselves while passengers battled a shortage of life-jackets.

Marine police and fishing and tourist boats responding to the ship's distress call managed to pull 94 passengers from the sea, Mersing police official Harun Arshad said.

Initial inquiries revealed engine trouble as the cause of the fire but police were questioning survivors to find out how and where it began as well as the exact number on board, he added.

All the people killed or hurt in the incident came from the Malaysian capital and Johor, the agency said, but did not say if any foreigners were aboard.