Dock workers at Sri Lanka's main container port called Tuesday for a boycott of cargo from neighbouring India amid worsening relations.
Ruling party-affiliated workers staged the protest at Colombo harbour, demanding that the government retaliate against politicians in India's southern state of Tamil Nadu who have called for trade sanctions against Sri Lanka.
"There is an anti-Sri Lanka campaign in Tamil Nadu," a union spokesman told reporters at the demonstration. "We want the port to stop handling cargo from south Indian ports."
However, the Sri Lanka Ports Authority said there were no plans for any boycott.
"The workers have expressed their anger but so far they have not resorted to an actual boycott," spokesman Nalin Aponso told AFP. "We're keeping a close watch."
The Colombo port handled 4.1 million containers last year, of which 70 percent came from Indian ports.
Politicians in Tamil Nadu state, which has seen daily protests against Colombo, passed a resolution last week urging New Delhi to stop treating Sri Lanka as a friendly country until it probes the "genocide" of ethnic Tamils.
Indian Tamils share close cultural and religious links with their kinsmen in Sri Lanka.
Rights groups have said Sri Lankan troops killed up to 40,000 members of the minority Tamil population in 2009 in the final months of the island's civil war -- a charge denied by Colombo.
The Indian government, which has traditionally been wary of upsetting its neighbour, was among 25 nations which last month supported a resolution at the UN Human Rights Council calling for a probe of alleged war crimes on the island.