Colombo – Amid growing international pressure for a ceasefire against Tamil rebels in north-eastern Sri Lanka, the government Monday ordered the army to stop using heavy weapons to avoid civilian casualties. "Our security forces have been instructed to end the use of heavy caliber guns, combat aircraft and aerial weapons which could cause civilian causalities," a statement from the president's office said.

It said the decision was made as the "combat operations have reached their conclusion."

"Our security forces will confine their attempts to rescuing civilians who are held hostage and give foremost priority to saving civilians."

The army and Tamil rebels had resumed fighting around the last rebel-held area, where thousands of civilians remain trapped, after the government rejected a rebel ceasefire offer, a doctor based in the area said Monday.

Dr Thiyagaraja Sathiyamoorthy, one of the few medics remaining in the zone controlled by the Liberation Tigers of Tamil Eelam (LTTE), told journalists via telephone that troops had launched operations to recapture the narrow strip on the coast area of Mullativu district, 395 kilometres north-east of the capital Colombo.

"I can hear the exchange of fire between the two sides and the people here have limited areas to go to safety," the doctor said.

He confirmed that the last ship carrying food and medical supplies reached the trapped civilians on April 2, and people were now facing severe shortages.

Earlier in the day the pro-rebel Tamilnet website said an operation had been launched around 3:45 am Monday (2215 GMT Sunday), and heavy gunfire was reported in the area.

Military officials confirmed they were continuing their operations but declined to comment whether they had stepped up the attack.

The LTTE rebels have claimed that an estimated 160,000 civilians are pinned down in the coastal area, but the government says there are only 20,000 civilians still trapped. Other sources say there may be around 40,000 people in the war zone.

"If the expected offensive goes forward, there will be more than 10,000 casualties as the area is densely populated and there is no cover from bombs, shells, and bullets," the Tamilnet quoted a press statement issued by the Tamils Rehabilitation Organisationa front organization for the LTTE.

Last week some 109,000 civilians fled from the combat zone into into the government-controlled areas, raising the total of number of refugees to 170,000 since January.

The military said it rescued 3,147 civilians from the combat zone Sunday and 53 rebel cadres including 23 child soldiers who had been recently recruited by the movement surrendered.

Tamil rebels announced a unilateral ceasefire Sunday, but Defence Secretary Gotabaya Rajapaksa rejected the offer to reciprocate.

The defence secretary, who is the brother of President Mahinda Rajapaksa, vowed to fight until the LTTE is crushed.

"That [ceasefire] is a joke. What is the need for a ceasefire when they are running away?" the defence secretary was quoted as saying in a statement issued by the President's Office.

"The LTTE must first lay down arms, surrender and let the people go," he said.

Visiting UN humanitarian chief Sir John Holmes also called for a humanitarian pause enabling civilians to leave the combat zone, but his call was so far ignored by the Sri Lankan government.

Holmes met with Foreign Minister Rohitha Bogollagama Monday to further discuss the trapped civilians' plight as well as measures to assist those who have already fled to government-controlled camps, but details of the meeting were not available immediately.

A scheduled joint press conference by Bogollagamma and Holmes was called off.

Meanwhile foreign ministers from three European countries are to visit Sri Lanka on Wednesday.

"Foreign Secretary David Miliband, together with his French counterpart Bernard Kouchner and Swedish counterpart Carl Bildt, will visit (Sri Lanka) on Wednesday," a statement from the British High Commission said.

The British Foreign Secretary on Sunday also called on government to announce a ceasefire enabling civilians who remained trapped in the conflict area to move to safety.

"The safety of civilians is of paramount importance and both sides must comply fully with international humanitarian law and ensure the protection of civilians at all times," Miliban said in a statement which was also released in Colombo.

The military says it is in the final phase of crushing the LTTE who have been fighting in the north and eastern parts of Sri Lanka for an independent homeland for minority Tamils from the Sinhalese majority for the last 25 years.(dpa)