The United Nations said on Thursday Tamil Tiger rebels had violated international law for refusing to allow local staff and their families to leave Sri Lanka's war zone.
The Liberation Tigers of Tamil Eelam (LTTE) are now cornered in less than 400 sq km in northern Sri Lanka along with what aid agencies say are around 230,000 people trapped between the separatist rebels and a massive Sri Lankan military onslaught.
"The United Nations in Sri Lanka has issued its strongest possible protest to the LTTE for their refusal to allow U.N. national staff and dependents to return from the Vanni with the present U.N. convoy," a U.N. statement.
The convoy went into the war zone, a region known as the Vanni, on Jan. 16 and was only able to leave on Thursday, the U.N. statement said.
"The LTTE's denial of safe passage is a clear abrogation of their obligations under international humanitarian law," the U.N. office in Sri Lanka said.
The LTTE could not be reached for comment.
Rights groups say the Tigers have forced civilians to stay in the war zone to provide a human shield, and is making some fight or work to build defences. The rebels have denied that.