A Channel News Asia report citing police said the attacker poured kerosene on Seng Han Thong and a temple chairman, then set them on fire. Seng, 58, was burnt on his face, neck and back.
The two men were admitted to the Burns Unit shortly after 1 pm, with Seng suffering burns on more than 10 per cent of his body, the report said.
It said police arrested the assailant. Prime Minister Lee Hsien Loong and Senior Minister of State Sadasivan Balaji visited Seng at the hospital.