Panaji, Sep 2 (IANS): As the state government tries to downplay the tar ball menace that has polluted several of Goa's famed beaches, an MP of the ruling Congress has asked union Minister of Environment and Forests Jairam Ramesh to probe the matter.

Congress Rajya Sabha member Shantaram Naik has asked the minister to send a team of experts to "decipher the exact cause" of the oil spill.

The spill has left an ugly, oily trail across several beaches like Calangute, Candolim, Colva and Velsao and raised concerns about the success of the forthcoming tourist season.

"One fact is apparently clear that it is the ships passing along the coastline which are the culprits (for the oil spill). They discharge their waste which either surfaces before being deposited on the seabed or the waste gets erupted in monsoon," Naik said in his letter, which was received by Ramesh Thursday.

"The question is whether the captains of the ships can flout the rules and cause damage to the coastlines of the countries they pass by," Naik said, asking Ramesh to dispatch a team of environment ministry officials to Goa to assess the exact cause and extent of damage caused by the tar balls, as well as suggest means to prevent such accidents in future.

Tonnes of slimy tar balls have polluted the Goa coastline even as state authorities started an extensive operation to clean the beaches, known for attracting nearly two million tourists to the state.

According to the marine experts, one of the common causes for the tar ball phenomenon is careless dumping of used oil by a passing ship.

The tourism department has described the 'tar balls on the beaches' as a regular phenomenon.