Indian Prime Minister Narendra Modi has reignited debate over a tiny island that was ceded to Sri Lanka more than 40 years ago.

The island of Katchatheevu lies 33 kilometers (21 miles) off the coast of India. In 1974, Prime Minister Indira Gandhi of the Indian National Congress ended a maritime border dispute by recognizing Sri Lanka's claim over the island.

On Monday, India's Foreign Minister Subrahmanyam Jaishankar said Sri Lanka had detained more than 6,000 Indian fishermen and 1,175 fishing vessels over the last 20 years.

A day earlier, Modi accused the Congress party of having "callously" given away the island to its neighbor.

"Weakening India's unity, integrity and interests has been Congress' way of working for 75 years and counting," Modi said on social media.

Winning votes in Tamil Nadu

Congress chief Mallikarjun Kharge hit back at the claims and said the 1974 deal was "based on a friendly gesture."

He accused Modi and the Bharatiya Janata Party (BJP) of reviving an old controversy in an attempt to curry favor with voters in Tamil Nadu, which will be among the first states to head to the polls on April 19.

Discontent has grown in the southern state over curtailed fishing rights, which has prompted two legal challenges against the 1974 agreement that are still before the Supreme Court.

Meanwhile, Modi's BJP is try to make inroads in Tamil Nadu, where it won none of the state's 39 seats in India's parliament at the last election and has has hardy any representation at the state level.

Modi's BJP is seeking a third term in power against a broad alliance of opposition parties led by the Congress in general elections begins in mid-April and runs through early June.

zc/lo (Reuters, EFE)