(Updates with Tiger comment, details) By Simon Gardner COLOMBO, June 5 (Reuters) - Sri Lankan fighter jets bombed a Tamil Tiger training camp in the rebel-held north on Tuesday, the military said, as Japan's peace envoy began a visit seeking ways to arrest an escalation in the two-decade civil war. In a separate incident, the military said a roadside bomb planted by suspected Tigers killed an elite police commando in the eastern district of Batticaloa. United States Ambassador Robert Blake and visiting U.S. disaster management officials were touring the district at the time, but were nowhere near the blast, a U.S. embassy spokesman said. "An air strike was launched on a Tiger military base this morning," a spokesman for the Media Centre for National Security said, declining to be named in line with protocol. "The camp has been destroyed." The Liberation Tigers of Tamil Eelam, who want to carve out an independent state in Sri Lanka's north and east, said the military had conducted two air strikes on their territory, but the bombs hit an abandoned farm and jungle and no-one was hurt. There was no independent confirmation of what the bombs hit. "The bombs fell near a populated area, but no civilians were hurt, luckily, and no Tigers were hurt," rebel military spokesman Rasiah Ilanthiraiyan said by telephone from the Tigers' northern stronghold of Kilinochchi. Yasushi Akashi, the peace envoy of Japan, Sri Lanka's chief financial donor, began a visit to the island on Tuesday, during which he will meet Rajapaksa and his brother -- the island's defence secretary -- as well as government officials and civil society leaders. Akashi also plans to visit camps housing thousands of internally displaced in restive Batticaloa. Japan played down any hopes of a breakthrough. "The possibilities are very low. This time it is a very difficult situation," said Hideaki Hatanaka, first political secretary at Japan's embassy in Colombo. Akashi would not visit the Tigers in their northern stronghold of Kilinochchi because of security concerns, he added. However, he would try to push forward an initiative to forge a cross-party consensus devolution proposal to end a conflict that has killed an estimated 4,500 people since last year alone, including hundreds of reported abductions and murders. U.N. ALARMED United Nations Secretary-General Ban Ki-moon voiced concern for the safety of aid workers in Sri Lanka overnight after the murder of two Red Cross volunteers, his office said. Two Tamil Sri Lanka Red Cross volunteers were taken away by men who identified themselves as policemen from a train station in Colombo on Friday. Their corpses were found dumped outside the capital two days later. "The secretary-general is deeply concerned about the security of civilians and aid workers in Sri Lanka and reminds all parties in the country that aid workers have a right to protection at all times," Ban's office said in a statement. Rights groups have reported hundreds of abductions and disappearances in recent months after the military and the separatist Tigers resumed a two-decade civil war in which nearly 70,000 people have been killed since 1983. President Mahinda Rajapaksa's office said on Monday the Red Cross volunteer murders were a bid to damage his and the government's reputation ahead of a meeting with the International Committee of the Red Cross in Geneva later this month. Police deny any involvement in the killings, discovered after Rajapaksa said most complaints about abductions -- many of which are levelled at state security forces -- were false.
