Beijing, Jan 8 (IANS): Fears of a growing environmental disaster in the East China Sea escalated as a tanker continued to be still ablaze and leak oil on Monday two days after colliding with a cargo ship.

On Saturday night, the Sanchi tanker, carrying 136,000 tonnes of Iranian oil, collided with a Chinese cargo ship, 165 nautical miles east of Shanghai, the BBC reported.

The 21-strong crew of the Chinese ship were rescued but Sanchi's crew, 30 Iranians and two Bangladeshis, remain missing.

The tanker had been carrying an ultra-light form of oil known as condensate which in the case of a spill can be more dangerous for the environment than regular crude.

"Condensate is more likely to evaporate and mix in with the water," John Driscoll of JTD Energy Services told the BBC.

"It also can be colour- and odourless - so it is a lot harder to detect, contain and clean up."

The extent of the spill and environmental hazard were still unclear.

The US Navy has sent a military aircraft to help China with the rescue efforts which have been hampered by the blaze and oil slick.

China has deployed several ships to carry out search-and-rescue operations while South Korea has also sent a coast guard ship and a helicopter.