A burning Iranian oil tanker adrift on the East China Sea sank on Sunday, hours after a massive fire and explosion. The oil spill is getting worse, and China is ready to tackle severe pollution and damage to the surroundings. CGTN's Su Xiaoxiao has more.

A sudden and powerful explosion turned the oil tanker to an erupting volcano on the ocean. Smoke was soaring thousands of meters high into the sky. A CGTN news team witnessed the explosion.

VOICE OF YANG LITIAN CCTV REPORTER "We can see Sanchi tanker has completely sunk. Nothing but debris and oil are still burning. A 10-square kilometers oil belt has been formed. It was only three-square kilometers two days ago. It is a very serious situation."

It's been a week since the Iranian oil tanker collided with a Chinese freighter on its route to South Korea. Three bodies were recovered, and 30 are still missing from the Iranian ship. Tehran says there is "no hope" of survival for the missing sailors. 21 sailors on the Chinese cargo ship survived. Now comes the impact on the environment, the ship was carrying 136-thousand tons of the light weight oil.

TENG DA CHINESE OCEANIC ADMINISTRATION "This is a rather severe marine accident I have come across in my career. Now the tanker has sunk, what comes next to the ecological system, the government should watch closely. They could face oil spill and deal with toxic materials emission."

China has dispatched eight ships to search for the missing and contain the fire. Chinese Foreign Minister Wang Yi has promised his Iranian counterpart that China won't give up on searching for survivors. And just one day before the tanker blew up, a four-men Chinese salvage team entered the wreckage. They retrieved two bodies and the black box. ROK, Japan and U.S. also joined the rescue operation. Su Xiaoxiao CGTN.