At least 63 LTTE militants and three security forces personnel were killed in raging ground battles since weekend while Tamil Tiger rebels on Monday shelled a main Sri Lankan military air base, linking the country to theembattled north.In fierce clashes in North-western Mannar on Monday, the Defence Ministry said the military killed 25 LTTE militants, including 16 in Palaikkuli.One soldier was also reportedly killed in the incident, the Media Centre for National Security (MCNS) said.In clashes at South of Adampan in Mannar, troops killed five LTTE cadres in confrontation, it said adding in another incident at west of Adampan, troops killed two rebels.The LTTE said they shelled the Palaly airfield in northern Jaffna peninsula, forcing it to was shut down for military and civilian traffic.Meanwhile, Sri Lanka Air Force fighter jets raided LTTE gun positions in the Kalmunai point in Paranthan in the northern part of the island, the Defence Ministry said.