COLOMBO (AFP) - Sri Lanka issued a stark warning to civilians trapped in fighting with Tamil Tiger rebels Monday, a day after shells hit a crowded hospital in the northeast combat zone, killing at least nine people. A government statement said the fight against the cornered Tigers was at "the decisive stage" and that it could not guarantee the security of tens of thousands of non-combatants living outside a designated "safety zone" in rebel-held territory. "The government calls on all civilians to enter the demarcated 'safety zone' as soon as possible," the statement said. "The government cannot be responsible for the safety and security of civilians still living among LTTE (Liberation Tigers of Tamil Eelam) terrorists," it added. A year-long military offensive has pushed the once-powerful LTTE back into 300-square kilometre jungle area on the island's northeast coast. The United Nations says up to 250,000 non-combatants are trapped in the area. The Sri Lankan government says the figure is closer to 120,000. Aid agencies say hundreds of civilians may already have been killed in the crossfire and scores more injured, including children as young as 10 days old. A hospital in the area with 500 patients, took direct hits in two separate shelling incidents on Sunday, aid agencies and medical workers said. At least nine patients were killed and 15 injured. "We're shocked that the hospital was hit, and this for the second time in recent weeks," said Paul Castella, head of the International Committee of the Red Cross delegation in Sri Lanka's capital, Colombo. The ICRC did not say which side was responsible for the shelling, but the army denied involvement, saying it was carried out by the rebels in a bid to "discredit" the military. "We know the exact location of the hospital. We will not hit it," said military spokesman Brigadier Udaya Nanayakkara. "We are ready at any moment to arrange safe passage for civilians in that area." With the Tigers on the brink of defeat, the government has rejected international calls for a ceasefire, saying it intends to wipe out the rebel force and finally end Asia's longest-running ethnic conflict. Tiger rebels took up arms in their fight for a separate Tamil homeland in 1972. There was heavy fighting in the narrow strip of land where the rebels have been cornered, the defence ministry said, with war planes bombing suspected Tiger positions. Military officials said jet aircraft carried out five bombing sorties on Monday but details were not immediately available. The ministry said a total of 46 Tiger rebels were killed in separate ground clashes, but did not say if security forces suffered any casualties. The government has accused the Tigers of using civilians as a human shield and preventing them from moving into the safety zone on the edge of the rebel-held territory. The Tigers insist the non-combatants are free to leave, but say they are scared of moving to areas under military control. T. Varatharajah, the regional director of health services stationed in the damaged hospital, said the shells had hit the staff quarters, the female ward, the mortuary and the kitchen. The doctor said many patients' relatives were also staying in the hospital grounds, bringing the number of people inside the compound to around 1,000. "Most of the staff have also moved in with their families," he added. The UN arranged an evacuation of some 350 wounded people and their relatives from the combat zone last week and negotiations are underway for the transfer of a further 250 patients from the hospital. The government has blocked any independent media access to the conflict area and to the camps housing those displaced civilians who have managed to flee the fighting.