The Ministry of External Affairs (MEA) on Tuesday expressed deep concern over the killing of Indian fisherman by the Sri Lankan Navy and said that Indian High Commissioner to Sri Lanka has taken up the matter with the prime minister of the country.

"Indian High Commissioner to Sri Lanka has taken up the matter with the Prime Minister of Sri Lanka and the Lankan Navy has promised a full and thorough investigation in to the matter," sources at the MEA said.

A 22-year-old Indian fisherman was shot dead on Monday allegedly by the Lankan Navy personnel while he was fishing in a mechanised boat at a short distance off Katchatheevu islet.

Hundreds of fishermen on Tuesday staged a demonstration at Thangachimadam in Rameswaram to protest the killing of an Indian fisherman allegedly by the Sri Lankan Navy.

The fishermen alleged that there was no proper coordination between Lankan and Indian officials on the issue of fishermen fishing in the Palk Strait.

They demanded the release of all Indian fishermen arrested by the Sri Lankan Navy and also the boats seized by them.

The Tamil Nadu government had recently protested the rise in the cases of its fishermen being arrested by Sri Lanka and said the Centre did "not seem to put adequate pressure" on Colombo regarding the matter.

Noting that currently there were 85 fishermen and 128 fishing boats in Lankan custody, Chief Minister Edappadi K Palaniswami had urged the Prime Minister to direct the External Affairs Ministry officials to take concrete action through diplomatic channels to secure their release.