The unarmed Sri Lanka Monitoring Mission (SLMM) said the military and the Liberation Tigers of Tamil Eelam (LTTE) had blocked access to areas to investigate rights abuses -- in itself a serious violation of the terms of the truce.

The monitors said in a ruling that the military had violated the ceasefire since late July when it captured rebel territory on the southern lip of the strategic northeastern harbour of Trincomalee.

The rebels had similarly violated the truce when they mounted offensive operations against the military in the northern Jaffna peninsula -- which is still besieged by Tiger artillery fire.

"Throughout the period (July 22-Sept 25), both parties have responded to the other party's actions in ways that are not conducive with the ceasefire agreement," Chief monitor Major General Lars Johan Solvberg said in the ruling.

"As a result of these actions, over 200 civilians have been killed and several thousand are internally displaced, creating a serious humanitarian crisis in the eastern and northern part of Sri Lanka."

The ruling also accuses both sides of a string of other serious violations, such as restricting the movement of civilians.

Solvberg told Reuters this week he was shocked and disappointed at the behaviour of both the rebels and the government.

The monitors have previously accused the security forces of being responsible for extrajudicial killings and the execution-style killings of 17 local staff of international aid organisation Action Contre La Faim in the east in August.