Inspector General of the Coast Guard S P S Batra said the spilled oil will reach the coast between Thal Knob and Alibaug in Raigarh district in the form of brown mosses.
"As per estimates the sheen is moving in the northeast- east direction. Brown mosses will continue to reach the coast between Thal Knob and Alibaug because of the prevailing wind and current conditions. However, it is unlikely to affect Mumbai," he said.
"Till now 80 to 100 tonnes oil must have leaked into the Arabian sea," he added.
Basra said the Coast Guard is spraying dispersant and breaking oil mosses into smaller patches to reduce environmental damage.
He said they have sprayed around 2,600 litres of oilspill dispersant till now, under the operation ''Paryavaran Suraksha'', undertaken after the leakage.
According to the Coast Guard officials, oil which was up to seven nautical miles, spread up to 12 nautical miles off the site today.
The oil sheen and broken patches are eight to nine nautical miles from the coast, while yesterday it was around 10 to 12 nautical miles, they added.
M V Rak, which was on its way from Indonesia's Tutung to Dahej in Gujarat with 60,000 tonnes of coal, had a 30-member crew of Indonesian, Jordanian and Romanian nationalities, who were rescued by the Indian Navy and Coast Guard personnel before it sank on August 4.