Sri Lanka said on Sunday that its Navy had not fired at fishermen hailing from Tamil Nadu last month, claiming that the incident occured well within the Indian waters.

Quoting a letter written by Tamil Nadu Chief Minister M Karunanidhi to Prime Minister Manmohan Singh on the issue, Lankan Foreign Minister Rohita Bogollagama said that the incident happened within Indian territory.

"I am very happy to know that the letter had been addressed to the prime minister of India from the Tamil Nadu chief minister in which he clearly states the location at which the incident occured. And going by the location on the southern tip of India, it is 15 nautical miles into the Indian waters, that this incident has happened and is totally in Indian waters," Bogollagama told NDTV.

He said the Sri Lankan Navy has 'never been associated with shooting any fisherman from any part of the world'.

Four Indian fishermen were killed and two injured on March 29 when they were fired upon.

Expressing his distress over the killings, Karunanidhi in his letter to the prime m, said the situation was likely to get out of control unless the Centre took some stern measures to make Indian waters safe for fishing by Indian fishermen.

He said an investigation should be conducted to find out the identity of the killers and their international connections.