COLOMBO (AFP) - Sri Lankan troops advancing on the last remaining pockets of rebel resistance killed at least 111 Tamil Tigers in separate ground and sea clashes on Saturday, the military said. Security forces recovered the bodies of 93 Tigers killed at Puthukkudiriruppu while another 18 guerrillas perished in a separate sea battle on Saturday, military spokesman brigadier Udaya Nanayakkara said. It is one of the biggest blows for the Tigers recently, Nanayakkara said referring to the military drive to crush Tigers who have been confined to a narrow strip of coastline in the district of Mullaittivu for several months. He said troops had also captured a 130 mm artillery gun which had been used by the Tigers to attack security forces moving in on them. There was no immediate comment from the Tigers. The assault has pushed the rebels into a 20-square-kilometre (eight-square-mile) patch of land in Mullaittivu. Earlier in the day, the navys special boat squadron sank one vessel belonging to the Liberation Tigers of Tamil Eelam (LTTE) while two others were destroyed by ground troops when they tried to beach, the military said. The military believed that at least 11 rebels were killed by the navy while another seven perished when the army directed ground fire at Tiger boats that were trying to get to shore. The defence ministry said two sailors were wounded and three naval craft slightly damaged during the confrontation. It did not say if troops suffered any casualties in the ground battles. Sri Lankan troops captured a key village from the Tigers on Friday after heavy fighting that left at least 44 guerrillas dead while another 13 rebels were killed elsewhere on the same day, the military said. The United Nations and foreign aid organisations say as many as 150,000 civilians may be trapped in the combat zone, although the Sri Lankan government insists the figure is less than half that. A top UN official, Walter Kalin, was visiting camps for war displaced people in the north of the island on Saturday, officials said. Kalin, the UN secretary generals representative on the human rights of internally displaced persons, spoke with people in the government-held town of Vavuniya who had fled the fighting. However, he did not travel to the front lines. His visit to Sri Lanka came as UN chief Ban Ki-moon again urged Tamil rebel leaders to allow trapped civilians to move freely out of the conflict area. The secretary general calls upon the LTTE leadership to allow civilians to leave the conflict area of their own free will, said a statement issued by UN spokeswoman Michele Montas in New York. The severe restrictions of the LTTE on their freedom of movement violate international law. The UN head also reminded the Colombo government of its responsibility to protect civilians, and to avoid the use of heavy weapons in areas where there are civilians, as promised. He said the Sri Lankan government should receive and treat displaced persons in accordance with international law, and work closely with the United Nations in meeting the protection and physical needs of displaced persons. At the height of their power in the mid-1990s, the Tigers controlled more than a third of the total land mass of Sri Lanka as they pushed for an independent Tamil homeland. Sri Lanka has said for months that its forces are on the verge of dealing a crushing blow to the Tigers in the decades-old ethnic conflict that has claimed tens of thousands of lives.