Beijing (CNN)Part of an oil tanker that has been ablaze for days off the coast of Shanghai exploded Wednesday, forcing rescue boats searching for 31 missing sailors to retreat, Chinese authorities said.
Oil tanker Sanchi partially explodes in East China Sea
The Panama-registered tanker, Sanchi, was carrying 136,000 tons -- around 1 million barrels -- of oil from Iran to South Korea when it collided with the Hong Kong-registered CF Crystal freighter in the East China Sea on Saturday evening. Since then, the tanker has been ablaze and drifting in the waters between Shanghai and southern Japan.
By Wednesday evening, the stricken ship had drifted 65 nautical miles southeast from the site of the collision, China's Ministry of Transport said. The front section of the SANCHI had exploded earlier Wednesday, at around 1.30 local time (12.30 a.m ET).
"Vessels at the scene have to stop putting out the fire and withdraw back to (a safe distance)," the statement said. "The fire extinguishing operation did not achieve the desired effect."
Thirty Iranian and two Bangladeshi sailors were onboard during the catastrophic collision. So far, no survivors from the tanker have been found and only one body has been recovered.
The CF-Crystal had been transporting food from the United States to the Chinese province of Guangdong, the China's Ministry of Transport said, adding that its 21 crew members has all been rescued.
A spokesman for the National Iranian Tanker Company, Iran's top oil shipping operator and a joint public-private company which owns and operates the Sanchi, told Iranian state media that China was not attempting to rescue the sailors, nor extinguish the blaze.
Mohsen Bahrami, spokesman for company, confirmed to CNN that he told the Iranian Students' News Agency, one of the country's state outlets, that "China did not help with the rescue efforts of the people on board the Iranian tanker."
He told ISNA that despite having firefighting assets in the area, Chinese authorities were not actively trying to extinguish the blaze.
"China has a lot of firefighting equipment and personnel near burning tanker but it is not using them," he said.
CNN has contacted the Chinese authorities for comment but has not yet received a reply.
China's Ministry of Foreign affairs said Wednesday that 12 vessels were searching for the missing sailors in the tanker's vicinity before the explosion, and efforts were continuing to clean up any spilled light crude.
The Japanese Coast Guard told CNN Thursday that it is sending at least one patrol ship and one aircraft to gather the information of the accident and the status of the area in order to issue navigation updates and warnings.
The Coast Guard does not currently plan on sending teams to contribute to either the rescue or firefighting efforts but confirmed that Chinese teams are working to extinguish the blaze.
With a length of 900 feet (274 meters) and displacing more than 85,000 tons, the Sanchi is almost as big as the US Navy's Nimitz-class aircraft carriers, according to the ship-tracking site marinetraffic.com.
Iran's Shana news agency reported that the Sanchi was managed by the National Iranian Tanker Company and that its cargo was worth around $60 million. Shana said the oil had been purchased by South Korean customers.