Chennai, Sep 29 (IANS): India should show "greater firmness" to force Sri Lanka to stop attacking and arresting Tamil Nadu fishermen on the sea, Chief Minister J. Jayalalithaa has said.

She also urged the central government to put diplomatic pressure on Colombo to secure the release of the Indian fishermen detained in Sri Lanka.

In a letter to Prime Minister Manmohan Singh Saturday, Jayalalithaa said: "The government of India has virtually abandoned its poor and defenceless fishermen to face an uncertain future caused by the risk of daily attacks and abduction at the hands of the Sri Lankan Navy.

"Unless the government of India displays greater fortitude and firmness and acts with alacrity through diplomatic channels to put pressure on Sri Lanka, there appears to be little chance of securing the prompt release of our fishermen or to avert such instances in future," she added.

She said that soon after she wrote Sep 20 suggesting a meeting of fishermen from India and Sri Lanka in December, 20 fishermen of Rameswaram in Tamil Nadu were detained by the Sri Lanka Navy.

They have been remanded in custody up to Oct 7 and lodged in a jail in Vavuniya, 254 km north of Colombo, she said.

According to Jayalalithaa, 136 fishermen from Tamil Nadu and their 29 boats continue to be in Sri Lankan custody.

She said 76 fishermen from Tamil Nadu apprehended by the Sri Lanka Navy on different dates were ordered to be deported by a Sri Lankan court this month. But they were yet to return home.

Sri Lankan authorities regularly detain Indian fishermen, overwhelmingly from Tamil Nadu, on the narrow sea dividing the two countries on charges of intruding into Sri Lankan waters.

The Tamil Nadu chief minister has repeatedly accused the Sri Lankan military of attacking the fishermen and seizing or destroying their boats.