Thousands of families converged on Kilinochchi when battles broke out elsewhere in the Wanni.

ECONOMIST: Sri Lanka's war

The human rights group urged both the government and Tamil Tiger rebels to allow international monitors into the northern Wanni region.

BBC: Amnesty in urgent Sri Lanka plea

Hicham Mandoudi, who heads the ICRC's Wanni operations, says many are exhausted after fleeing several times since hostilities escalated in July, each time abandoning more of their belongings.

ECONOMIST: The martial mood intensifies

However, they haven't had the same success as last month when they swept through a huge area of government-held territory in the Wanni region further south, meeting little resistance.

BBC: Tigers push northwards

The ICRC is the only international humanitarian agency left in the Wanni, after the UN and others pulled out in September, when the government said it could not guarantee their safety.

ECONOMIST: The martial mood intensifies

Last month, the Tigers captured a large area of land, over-running several army bases in the Wanni region, and inflicting one of the most serious defeats on the government since the start of the conflict.

BBC: Tamil Tigers attack pass