It collided with the freighter CF Crystal that was carrying grain from the United States about 184 kilometers off China's coast near Shanghai.
Global search efforts have involved numerous Chinese vessels, a South Korean coast guard vessel and a fixed-wing aircraft.
Hard weather and sea conditions have hampered search efforts in recent days with only one body recovered - that of an Iranian national that Sanchi'sowners National Iranian Tanker Company (NITC) believe to be one of the vessel's crew. On Tuesday (9 January) NITC reportedly told Bloomberg that some of Sanchi's 31 missing crew members who remain missing could still be alive in the tanker's engineroom, which lies some 14 m below the waterline and "is not directly affected by the fire".
Firefighting operations were suspended on Wednesday (10 January), after an explosion rocked the vessel. The ship was carrying condensate, a highly flammable ultra-light crude, to deliver to South Korea when it collided with a Chinese freight ship on Saturday.
South Korea's Ministry of Oceans and Fisheries warned on Wednesday the tanker could burn for up to one month, potentially expelling the tanker's bunker fuel, or the heavy fuel oil that powers a ship's engines and contaminating the waters.
Chinese state media CCTV showed footage on Monday of boats dousing the flames with water as plumes of thick dark smoke continued to billow from the tanker.
The Panamanian-registered vessel had a crew of 30 Iranians and two Bangladeshis.
According to the VesselsValue database, Sanchi is owned by the National Iranian Tanker Company and CF Crystal is owned by the Changhong Group HK Ltd.
"We believe flames would last for two weeks or a month considering previous cases of oil tank accidents", said Park Sung-dong, an official at the ministry.
China's Ministry of Transport and Maritime Safety would not comment when asked if the fire was out.
Efforts to extinguish a fire and rescue survivors on a stricken oil tanker have been hampered because the vessel keeps exploding.
Trying to contain a spill of condensate, which is extremely low in density, highly toxic and much more explosive than normal crude oil, may be hard.
The remains of one of the 32 mariners on board the tanker has been found, Iranian and Chinese officials confirmed.
Euronews has gathered the despair of relatives: "We want worldwide aid for our children who are probably alive in the tanker - says a mother - help them, they are human beings who need help right away.We appeal to the global community. see our loved ones soon ".