On January 6, the Panamanian flagged vessel had been en route from Iran to Korea when she collided with the bulk grain carrier CF Crystal, which was laden with 64,000 tonnes of grain en route from the United States to China, approximately 160 nautical miles east of Shanghai.
Strong winds had pushed it away from the Chinese coast, where the incident happened, and into Japan's exclusive economic zone.
Before the tanker sank, the SOA said the impact of the oil spill might be limited because light crude evaporated quicker than other forms of oil.
"Given that the fuel tanks in these sorts of vessels are located close to the engine room, it is likely that the fuel tanks have remained intact since the initial collision", said Paul Johnston, a research fellow at the University of Exeter. Another body, presumed to be one of the Sanchi's sailors, was found on Monday and brought to Shanghai for identification.
Three bodies have been recovered and the rest of the 32-member crew are presumed dead, said Iranian officials.
The oil spill from NITC oil tanker Sanchi has spread significantly across the East China Sea.
The tanker was carrying 136,000 tonnes of ultra-light crude oil from Iran to South Korea when it collided with the Hong Kong-registered CF Crystal freighter in the East China Sea on January 7.
Japanese authorities lost track of the tanker as of 8.40am GMT on Sunday. The ship's last confirmed location was about 315 km (195 miles) west of Sokkozaki on the island of Amami Oshima.
The Shanghai Maritime Bureau said these, along with a South Korean patrol boat, were among the vessels carrying out emergency response work on Monday. If trapped underwater, however, it could seriously harm the marine environment. "The stricken tanker is leaking its cargo of condensate, which is toxic to marine mammals, fish, sea turtles and seabirds", WWF said in a statement.
As with all major oil spills, time is of the essence.
"Surveillance and assessment by authorities is critical to understand the extent of the potential environmental impact and for deciding on the appropriate next steps in terms of salvage and recovery of the potential condensate spill", Johnston wrote in a Greenpeace news release.
Yu Zhirong, a former deputy of the East China Sea unit of China Marine Surveillance, told business magazine Caixin the Sanchi should have been bombed or torpedoed, causing an explosion that would burn up the remaining oil and limit the amount the seeped into the ocean.
A Suezmax tanker can hold a maximum of 5,000 tonnes of bunker fuel.
"It is possible that we will see chronic low volume leakage over a period of time at the seabed".