MT Samudera's engine room caught fire at 2.40pm (local time) but the Southern region Malaysia Maritime Enforcement Agency (MMEA) was only alerted of the situation at 4.40pm, a Malaysian maritime official said.
The 22 crew all-Indian nationals are currently undergoing routine medical observation at the Pontian Hospital, The New Straits Times reported quoting the official.
The tanker is still on fire with the operation to douse the flame ongoing.
"The crew said the fire started at the engine room about 2.45pm and spread rapidly, though they tried to put it out. They also said that they were not ferrying any combustible items, or fuel. We will conduct checks tomorrow to estimate the extent of damage," the MMEA official said.