WHEN a small bomb exploded on a Philippine Airlines (PAL) flight over Japan last December, killing one passenger and wounding five others, it sparked the biggest terrorist alert at Kai Tak since the Gulf War. That state of readiness has been maintained, despite the arrest of suspected mastermind Ramzi Ahmed Yousef in mid-January, because of fears terrorism could be about to take hold in Southeast Asia in the same way it has menaced the West for at least 30 years. Hong Kong officials, civilian experts and foreign affairs specialists blame the growing threat on rising fundamentalism. They say it stems from increased Iranian influence over regional Muslim separatist movements, and has been exacerbated by a lack of intelligence sharing in Asia and Washington's hardline policy following the World Trade Centre bombing in 1993. The sarin attack on Tokyo's subway system has compounded fears terrorists might have access to chemical weapons, the 'poor man's atomic bomb', and could unleash them on any city in the world. Steve Vickers, head of operations in Asia for risk and crisis management company Kroll, blames the rise in attacks partly on a lack of communication between countries. 'The intelligence exchange is not up to the task, unlike in Europe and North America,' Mr Vickers said. 'Here in Asia, the integrity in law enforcement is lacking and from time to time tensions are high between neighbouring countries.' Mr Vickers said countries such as Singapore and the Philippines needed to co-operate even if they were not on the best of terms. Meanwhile, a foreign diplomat based in Hong Kong said the hand of Teheran, which the US has put on top of its terrorism list, can be seen in some of the attacks in Southeast Asia. 'There is a wave of terrorism sponsored by Iran and it is all done very professionally,' the diplomat said. The link appears to be bomb mastermind Yousef. He is suspected to be involved in operations in Pakistan, the Philippines, Thailand and the US. Last week, Philippine investigators said Yousef, also the alleged mastermind in New York's World Trade Centre bombing, conspired with Filipino Muslims to kill Pope John Paul II, blow up the PAL jet and to attack embassies in Manila and elsewhere. The investigators also claim to have established that Yousef, who has been extradited by Pakistan to the US, maintained direct links with the Muslim fundamentalist group, Abu Sayyaf. The Abu Sayyaf is linked to terrorist attacks in the southern Philippines. There have also been at least 15 bombings in Thailand since the election of Prime Minister Chuan Leekpai's government in September 1992, in which nine people have been killed and more than 60 injured. Most have been blamed on the Pattani United Liberation Organisation, a Muslim separatist group based in the south of the country, but none have been solved and some analysts have blamed the unclaimed attacks on right-wing groups linked to the military. Even on the mainland, where the Government has historically moved swiftly against insurgents, Muslim separatists have exploded at least three bombs over the past three years in the remote Xinjiang region of northwest China. Wang Lequan, the region's acting party chief, says the movement has little popular support, but what Beijing is most concerned about is the potential for involvement from the neighbouring Islamic states of Pakistan, Afghanistan and the former Soviet Central Asian republics.