Ramesh said, replying to a short-notice question in the Rajya Sabha: "I can assure the house that the polluter must pay and the polluter will pay."
The environment minister said the Maharashtra Pollution Control Board has asked the National Institute of Oceanography (NIO), Goa, and the National Environment Engineering Research Institute (NEERI), Nagpur, to look at comprehensive environment impact assessment.
"We are expecting to get the first report in four weeks and the next in three months. This report will be the basis for compensation," he said.
Panamanian cargo carrier MSC Chitra and a St. Kitts ship, MV Khalijia-III, collided Aug 7 outside the Mumbai harbour, barely five km from south Mumbai.
An estimated 2,000 litres of oil spilled from the grounded ship during the three days since its collision.
On a query related to compensation to fishermen affected by the oil spill, Ramesh said: "Central Marine Fisheries Research Institute, Cochin, has been asked to make a quick impact assessment on fishermen and it will be ready in two weeks."
"The process of filing compensation is a long-drawn one. But we cannot wait to give compensation to fishermen. Immediate compensation when identified will be provided to them," he added.
The minister said the Maharashtra pollution board has invoked the Environmental Protection Act, 1976, and three complaints have been filed.
Ramesh said he would not be able to testify to the safety and efficacy of the fish being caught in the area.
"There has been substantial impact on the fish population. Water samples have been taken and are being tested for contamination. Fish has started to come in Mumbai from other parts of the country," he said.
Ramesh said it is safe to eat fish in Mumbai as long as it is not caught in the contaminated water.