Suzana Sabljic Vienna Senior UN inspectors arrived in Syria yesterday to investigate US allegations that Damascus was building a clandestine nuclear reactor before an Israel air strike destroyed it in September.

Syria denies the accusations, saying the desert site housed an ordinary military building under construction.

Washington says the al Kibar project was camouflaged to hide its nature and nuclear analysts say satellite pictures since the bombing show it was bulldozed in a possible effort to remove incriminating evidence.

The International Atomic Energy Agency (IAEA) has indicated that uncovering the truth now could be difficult.

IAEA chief Mohamed ElBaradei has condemned the raid by Israel - believed to be the Middle East's only nuclear-armed power - saying it undermined the agency's mandate. "It is doubtful that we will find anything there now, assuming there was anything there in the first place," he said.

The IAEA put Syria on its watch list in April after receiving photographs from the United States, said to show a reactor that could have yielded fuel for plutonium bombs.

Washington said Syria, an ally of Iran whose own nuclear programme has been under investigation since 2003, had almost completed the plant with North Korean help.

Iran's defence minister, meanwhile, warned of an "unlimited destructive" response if Israel attacks his country. Mostafa Mohammad Najjar said "Iran will strongly counter any hostile action with a destructive response, considering all options regardless of time and place".

The New York Times said on Friday more than 100 Israeli fighter jets took part in a Mediterranean exercise this month, apparently a rehearsal for real missions over Iran.-AP