MANILA, Jan 9 (Reuters) - The brother of the Philippines' most wanted man said on Tuesday he was confident his sibling, head of the country's most dangerous Muslim rebel group, was still alive despite reports he may have been killed. DNA tests are currently under way to see if a decomposing body found by government troops in December on the remote southwestern island of Jolo was Khaddafy Janjalani, chief of the Abu Sayyaf group. But Hector Janjalani told local television station ABS-CBN that reports his brother was dead were fabricated so that a U.S. bounty of $5 million could be collected. "Why would I agree (to give them DNA samples) when I am certain that he is still alive?," he said. "What could happen is that, because of the hefty reward ... they will make it appear that it is positive (the DNA test). "Not only will they get money, but it will also earn them brownie points," Janjalani said. ABS-CBN said Hector had last spoken to his brother in 2000. Janjalani, believed to be 31, is on the U.S. Federal Bureau of Investigation's list of most wanted terrorists. Tissue samples from the body have been given to an FBI team and a U.S. embassy spokesman said the results would be known later this month. SCEPTICAL Some Philippine intelligence officers, speaking on condition of anonymity, have said the body was unlikely to be Janjalani's because there were reported sightings of him in October, a month after the supposed gun battle that killed him. "We are 90 percent sure it was not him," said one. Defectors from the Abu Sayyaf led Philippine marines to the grave on Jolo last month and claimed Janjalani was shot in the neck after a skirmish with the military in September. His death would be an important break for the Philippines, which has deployed over 8,000 troops to flush out the Abu Sayyaf and members of regional terror network Jemaah Islamiah, who are using the country's remote islands as bases. Despite continuing government offensives, Abu Sayyaf is believed to be responsible for recent bombings in the south. The Australian embassy has warned that militants could launch more attacks when the Philippines hosts a regional summit this week. Janjalani is the younger brother of the Abu Sayyaf's late founder, Abdurajak Abubakar Janjalani, who was shot by police on the southwestern island of Basilan in 1998. The Abu Sayyaf claimed responsibility for the Philippines' worst terror attack in February 2004 when a bomb crippled a ferry near Manila, killing more than 100 people, and for coordinated bombings in Manila and Mindanao in February 2005 that killed 10. (Additional reporting by Manny Mogato)