The UN is under fire for what critics say is an inadequate response to the plight of civilians caught in fighting in Sri Lanka.Tens of thousands of people are wedged into a sliver of land in the north of the island as Sri Lankan troops tighten the noose around Tamil Tiger rebels. Despire mounting fears about civilian casualties the UN Security Council only managed to issue an informal statement expressing its concern. After a meeting yesterday John Sawers, the UK ambassador to UN, said: “We call on the LTTE to stop using civilians as human shields, to allow a UN-assisted civilian evacuation from the area and to cease all violence and seek a poltical solution to their concerns.” Humanitarian groups believe the actions of both the rebels and the Sri Lankan army are threatening civilians. They want they UN to take a tougher line. Robert Templer of International Crisis Group said: “What is clear is that both siders are in violation of humanitarian law, and yet it seems that neither side is being threatened with being called to account.” Diplomats say the UN is unable to take further action because Security Council members Russia and China view the conflict as in internal Sri Lankan affair that does not threaten the international community.