Najib, who is also defence minister, added Malaysia remained committed to assisting Thailand to resolve an insurgency raging in the country that has left more than 1,900 people dead over three years, amid a recent surge in deadly attacks.

 Suspected separatists Wednesday set alight Thailand's largest rubber warehouse in the troubled deep South, which is jointly owned by Malaysians and Thais.

 "If it is concerning the safety of Malaysia firms, it is incumbent on the host country (Thailand) to safeguard the security of foreign investors, in as much as it is our responsibility to safeguard the security of those investing in Malaysia," he told reporters.

 The fire occurred as three more people were killed in fresh attacks across Thailand's Muslim-majority provinces, Thai police said Wednesday. The southern region was still reeling from synchronised weekend raids that left nine dead.

 Predominantly Muslim Malaysia shares a common border with southern Thailand. The region has a history of separatist violence, ever since Thailand annexed it a century ago. It was previously an autonomous ethnic Malay sultanate.

 Najib said that despite the surge in violence, Malaysia was determined to help Thailand resolve the crisis.

 "We still hold to the understanding that was reached when Malaysian Prime Minister Abdullah Ahmad Badawi met his Thai counterpart Surayud Chulanont recently.

 "At this stage our offer to help calm the situation still stands. But it is, however, up to the Thai government to come up with proposals for our help," he said.

 Ties between mainly Muslim Malaysia and Buddhist Thailand were badly strained under ousted Thai premier Thaksin Shinawatra, who accused Malaysia of failing to prevent insurgents from crossing the border to stage attacks.

 Since Thaksin's ouster in September, Surayud has made a priority of restoring peace in southern Thailand and of improving relations with Malaysia.

Agence France Presse