Sri Lankan troops have made fresh advances into the small patch of territory held by the Tamil Tigers, the defence ministry said Tuesday.
News of the military advance come as the Tamil rebel group accused government forces of killing at least 45 civilians in a fresh artillery and mortar attack.
The Liberation Tigers of Tamil Eelam (LTTE) said a makeshift hospital at Mullivaikal was hit early Tuesday, and that those who were wounded in a shelling over the weekend were hit again.
"Heavy artillery and mortar attacks this morning hit the hospital and 45 people were killed there," LTTE spokesman S. Puleedevan said by telephone. "Most of them were those injured in Sunday’s attacks."
Reports of fresh fighting comes amid mounting international alarm over large-scale civilian deaths over the weekend due to shelling by the Sri Lankan army.
The United Nations has called for an immediate end to Sri Lanka’s fighting after describing the weekend shelling of civilians as a "bloodbath" in which over 100 children were killed.
UN Secretary-General Ban Ki-moon urged the Colombo government "to explore all possible options to bring the conflict to an end without further bloodshed" and asked the separatist Tamil Tiger rebels to agree to a halt in the fighting.
"The secretary-general is appalled at the killing of hundreds of civilians in Sri Lanka over the weekend," his office said in a statement.
"Thousands of Sri Lankans have already died in the past several months due to the conflict, and more still remain in grave danger."
Artillery strikes on the small stretch of coastline still held by the Tamil Tiger guerrillas in the northeast of the island nation have caused major casualties among the tens of thousands of non-combatants, both sides reported.
"The large-scale killing of civilians, including the death of over 100 children, over the weekend shows that the bloodbath scenario has become a reality," Gordon Weiss, the UN spokesman in Colombo, told AFP.
The rebels said the civilians had died as the military pressed ahead with its offensive, but the defence ministry accused the Tigers of firing mortars to create a humanitarian crisis and attract foreign intervention.
"They are bombarding their own civilians with heavy weapons to lay the blame on the Sri Lankan forces," the ministry said in a statement.
The Tigers denied the charge through their former chief arms smuggler, Selvarasa Pathmanathan, who urged the international community to intervene and prevent further loss of life.
Pathmanathan, who is better known as K.P., insisted that over 2,000 civilians had been killed in the weekend violence which he described as the "most brutal episode" in the drawn-out conflict.
The government Monday said 250 civilians had been killed or wounded in the attacks blamed on the rebels, adding that it had lodged an official protest against the UN’s "bloodbath" description.
The pro-rebel Tamilnet website said that the weekend death toll had risen to 3,200.
Casualty claims from the war zone are impossible to verify as journalists and international monitors are not allowed to travel freely in the area.
Sri Lanka’s government believes its soldiers are on the verge of defeating the Liberation Tigers of Tamil Eelam (LTTE) after 37 years of conflict.
At the height of their power in 2006, the Tigers — who want an independent Tamil homeland in the Sinhalese-majority island — controlled roughly a third of the island.
The Tigers have since been driven back on to a sliver of land on the northeastern coast, where the UN has accused them of holding up to 50,000 Tamil civilians hostage.
Sri Lankan leaders have refused international calls for a ceasefire, despite reports from the UN last month saying up to 6,500 civilians may have been killed and 14,000 wounded in fighting since January.
Human rights and conflict prevention groups Monday urged Japan, which is Sri Lanka’s largest aid donor, to "shoulder its responsibilities" and confront the worsening humanitarian crisis in the country.
The UN Security Council was due later Monday to take up informally the humanitarian situation in Sri Lanka, diplomats in Colombo said.
British Foreign Secretary David Miliband told reporters in New York ahead of Monday’s meeting that the civilian situation in Sri Lanka merited the attention of the UN at all levels.
In Britain, hundreds of ethnic Tamil protestors broke through police lines and blocked traffic Monday outside parliament in central London to press for a halt in the fighting, witnesses and a police spokeswoman said.
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