New York/Colombo - More than 100,000 people are in mortal danger in Sri Lanka if security forces continue their offensive against dug-in rebels, the United Nations warned Wednesday.

John Holmes, the UN emergency relief coordinator, appealed to the Sri Lankan military to extend its holiday pause of operations against the Liberation Tigers of Tamil Eelam.

"The situation is simply catastrophic," said Holmes, who warned of a bloodbath if the army mounts what is expected to be one last tightening of the shrinking perimeter around the rebels.

Earlier Wednesday, the security forces resumed military operations in the north-eastern part of the country, ending a 48-hour suspension of military operations to mark traditional New Year celebrations.

A spokesman for the Sri Lankan military said it would continue with operations aimed at rescuing what the government estimates are 50,000 civilians who remain trapped in Mullativu district, 395 kilometres north-east of the capital.

It was not clear why the UN puts the number at twice that figure.

According to local estimates, the Tamil rebels retain control of an area less than 20 square kilometres where the civilians are held. But Holmes estimated the area at only 14 square kilometres.

Holmes charged that the rebels were using civilians as their protective shields. He said the 48-hour pause was not long enough to bring enough civilians out of danger, or to deliver humanitarian aid.

During the 48-hour period in which the military suspended offensive operations at least one soldier was killed by sniper fire by the rebels and three others were injured.

Tamil rebels called for a permanent truce Tuesday, but the Sri Lankan government has not accepted the offer.(dpa)