The other 31 crew members may be caught in the tanker's engine room, Mohsen Bahrami, spokesman for the crisis committee following up the situation of the missing Iranian seamen, told reporters.
To have access to the crew, the fire should be tamed soon, Bahrami said.
Chinese officials are very cautious dealing with this issue, so Iran has asked Japan to help, he added.
An Iranian tanker carrying condensates collided with a Chinese freight ship in East China coast on Saturday night, and the 32 members of the crew have gone missing. One body was found on Monday.
Bahrami said an American company has expressed readiness to help control the incident, but it was not equipped enough to bring the help soon.
The found body transported to China's Shanghai Port belongs to an Iranian crew, but his identity is not clear yet, the official said.
The tanker is still burning after three days.