A foreign cargo ship, which collided with another vessel about 10 km off Mumbai harbour on Saturday, tilted further on Monday, spilling oil for the third day as the Navy and Coast Guard made hectic efforts to contain the leak.

"MSC Chitra has tilted 80 degrees and the total oil spill is nearly 50 tons," Arun Singh, commandant (operations) of the Coast Guard told PTI.

He said so far, 300 containers carrying oil have tumbled into the water.

Maharashtra Chief Minister Ashok Chavan undertook an aerial survey of the oil spill on Monday.   

A worried Chavan said, "This is a serious issue. The Coast Guard and the defence people are looking into it. We have already filed cases against the captains of the two ships which are from abroad."

"I would say the state and the Union government is doing its best. Definitely it is a matter of concern and we have advised the people in that area not to go in for fishing because fishes and the marine life in that area is bound to be affected by this oil slick. We are trying to contain it as far as possible," he added.