India was accused yesterday of complicity in the killing of an estimated 20,000 civilians in the last stages of Sri Lanka’s 26-year war against the Tamil Tigers.

Major-General Ashok Mehta, a former commander of Indian peacekeeping forces in Sri Lanka, said that India’s role was “distressing and disturbing”. Two international human rights groups said that India had failed to do enough to protect civilian lives.

“We were complicit in this last phase of the offensive when a great number of civilians were killed,” General Mehta, who is now retired, told The Times. “Having taken a decision to go along with the campaign, we went along with it all the way and ignored what was happening on the ground.”

Despite being home to 60 million Tamils, India has provided Sri Lanka with military equipment, training and intelligence over the past three years, diplomatic sources told The Times. More controversially, it provided unwavering diplomatic support and failed to use its influence to negotiate a ceasefire for civilians to escape the front line, they said.

India joined a bloc led by China and Russia at a special session of the UN Human Rights Council last week to thwart a proposal for a war crimes inquiry, and instead supported a resolution praising Sri Lanka. In January India voted in favour of a war crimes inquiry into Israel’s operation in the Gaza Strip, which killed an estimated 926 civilians.

General Mehta said that the Indian Government, led by the Congress Party, wanted to counterbalance China and Pakistan, its main regional rivals, which had each increased arms sales to Sri Lanka in the past few years. It also wanted to avenge the Tigers’ assassination in 1991 of Rajiv Gandhi, the Prime Minister and late husband of Sonia Gandhi, the current Congress leader, he said.

Brad Adams, Asia director of Human Rights Watch, said that neither reason justified failing to act when the Red Cross warned of an “unimaginable humanitarian catastrophe”. India “could have saved many lives if it had taken a proactive position — and it would not have affected the outcome of the war,” he said.

Sam Zarifi, Asia Pacific director of Amnesty International, said: “India . . . simply chose to support the [Sri Lankan] Government’s notion that it could kill as many civilians as it would take to defeat the Tigers.”

India says that it provided Sri Lanka with non-lethal military equipment and sent officials repeatedly to persuade the Government to protect civilians. “We’ve consistently taken the line that the Sri Lankan Government should prevent civilian casualties,” a Foreign Ministry spokesman said.

However, President Rajapaksa of Sri Lanka told NDTV: “I don’t think I got any pressure from them. They knew that I’m fighting their war.”

Mr Rajapaksa told The Week magazine that he planned to visit Delhi next month to thank Indian leaders. “India’s moral support during the war was most important,” he said.

Diplomats, human rights activists and analysts say that Delhi either did not use its full diplomatic force or, more likely, gave Colombo carte blanche to finish the war. India’s only real concerns, they said, were that the conflict should not create a flood of refugees to India. Some raised questions about Vijay Nambiar, a former Indian diplomat, who is chief of staff to Ban Ki Moon, the UN Secretary-General. The Times revealed last week that Mr Nambiar knew about but chose not to make public the UN’s estimate that 20,000 civilians had been killed, mostly by army shelling.

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