(Adds appointment of ex-Tiger to government post, paras 11-13)
COLOMBO, March 9 (Reuters) - Sri Lankan soldiers killed at least 180 elite Tamil Tiger fighters carrying out waves of counterattacks, and the pace of refugees fleeing the tiny war zone picked up speed, the military said on Monday.
Heavy combat erupted over the weekend, suggesting the Liberation Tigers of Tamil Eelam (LTTE) were mounting a desperate defence against a military onslaught that has confined them to 45 sq km (17 sq mile) in the Indian Ocean island's northeast.
Since Saturday, the LTTE's elite Charles Anthony Brigade and Radha Regiment have attempted to punch through the army's frontline, the military said.
"Now they have not held back. Their elite fighters have been deployed to stop troops from entering those areas," military spokesman Brigadier Udaya Nanayakkara said. A total of 180 bodies had been found since the weekend, he said.
The Radha Regiment is the personal protection unit for LTTE leader Vellupillai Prabhakaran, whose whereabouts are unknown.
The pro-rebel website www.TamilNet.com, quoting an unnamed source, reported the LTTE had killed a "considerable number of soldiers" in a weekend artillery attack. Nanayakkara acknowledged some soldiers had been killed: "We have suffered casualties, but we are not releasing the numbers."
Both sides in the past have distorted battlefield figures to their advantage, and independent confirmation is difficult since the war zone is normally sealed off to outside observers.
Also over the weekend, at least 676 civilians escaped the war zone, some on foot but the vast majority by boat, Nanayakkara said. The Red Cross estimates 150,000 people are still trapped, but the government says the number is no more than 70,000.
After 25 years of off-and-on civil war, Sri Lanka's military is racing toward a final battle to crush a separatist group that has landed on numerous terrorism lists in its fight to establish a separate homeland for Sri Lanka's minority Tamils.
EX-TIGER NOW MINISTER
Giving a glimpse of the post-war political landscape, President Mahinda Rajapaksa appointed the former No. 2 Tiger as a non-cabinet minister for national integration and reconciliation late on Monday, the president's office said.
Parliamentarian Vinyagamoorthi Muralitharan, better known by his nom de guerre Karuna Amman, was sworn in by the president as he and around 2,000 Tamils from eastern Sri Lanka joined the president's ruling party.
Muralitharan defected from the LTTE in 2004, taking nearly 6,000 fighters with him and has pulled off a remarkable political transformation for a man who narrowly escaped war crimes charges while he was in a British jail last year for visa fraud.
Also on Monday, the military said the LTTE shelled near a ship flying the flag of the International Committee of the Red Cross (ICRC) that had landed food and aid in the no-fire zone.
The ICRC said the ship was not hit and was later sent back to port by the navy because of bad weather.
"We have no reason to believe the cargo vessel was directly targeted," spokeswoman Sophie Romanens said. "Shelling is going on all over the place, so it is not possible to see who fired."
The Tigers could not be reached for comment but have denied accusations from witnesses and aid agencies that they have attacked civilians or fired artillery from the no-fire zone. (Additional reporting by Ranga Sirilal; Editing by Jeremy Laurence)
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