A fugitive Malaysian explosives expert is believed to be responsible for a number of bomb threats made recently to several oil refineries on Indonesia's Borneo island, police said.

Indonesia's police chief General Da'i Bachtiar said the threats were made by an unnamed group of Muslim radicals led by Azahari Husin, who is wanted in connection with the Bali bombings and other attacks.

"Based on our evaluation and analysis, it was still that group," Bachtiar said, according to the state Antara news agency.

Expatriates workers

He gave no details of which oil refineries on Borneo - many are associated with foreign oil companies employing expatriates - had received the alleged threats.

Husin is a former university professor who has been eluding police arrest with his compatriot Noordin Mohammed Top after allegedly taking part in the October 2002 Bali bombings in which 202 people, mostly foreign tourists, were killed.

The two are also the prime suspects in the Jakarta Marriott hotel attacks in 2003 in which 12 people died and the bombing outside the Australian embassy in Jakarta that killed 12 people in September 2004.

Both attacks have been blamed on the Al-Qaeda-linked Jemaah Islamiah group.