Iran's Special Task Force spokesman Mohammad Rastad said testimony from crew on the CF-Crystal as well as from rescue workers, suggested the Sanchi's crew likely died early on from a massive blast and the ensuing release of toxic gas, state media reported.
All 21 Chinese crew members of the CF Crystal, which was transporting grain to Guangdong Province in southeastern China from the United States, were rescued, the Ministry of Transportation in Beijing said.
A burning Iranian tanker listing for days off the coast of China after a collision with another vessel sank Sunday, with an Iranian official saying there was "no hope" of survival for the 29 missing sailors onboard.
An Iranian oil tanker that has been ablaze for nearly a week after colliding with a cargo ship off the coast of China today sank with no hopes of finding any survivors among the 32 crew members.
A reporter with China's state television CCTV aboard a plane from the State Oceanic Administration reported seeing wreckage from the Sanchi, oil on fire, and spilled fuel covering a 10-square-kilometre (3.9-square-mile) area.
It remains unclear if there has been a significant oil leak into the sea.
But the Sanchi, carrying almost 1 million barrels of a gassy, ultra-light oil bound for South Korea, burst into flames.
Iran's Shana news agency reported that the Sanchi was managed by the National Iranian Tanker Company and its cargo was worth around $60 million. Until yesterday three bodies were recovered. Shana said the oil had been purchased by South Korean customers. A Chinese salvage team recovered two bodies from the deck of the tanker on Saturday. However, the condensate oil the ship was carrying readily evaporates or burns off in a fire, reducing the chance of a major oil spill.