Battle-hardened guerrillas of the Moro National Liberation Front (MNLF) have sailed from the Philippines to reinforce followers of the Sulu sultan who are battling Malaysian forces, one of their leaders said today.

"Many have slipped through the security forces. They know the area like the back of their hands because they trained there in the past," said Muhajab Hashim, chairperson of the MNLF's Islamic Command Council.

"We are expecting more of them to join (the fighting) even if our official instruction is for them to refrain from going," he added.

NONE He could not say how many MNLF fighters had managed to slip through naval cordons set up by the Philippines and Malaysia, but said "thousands" had earlier expressed interest in joining some 200 followers of the sultanate, led by Raja Muda Azzimuddie Kiram.

The Islamic Command Council oversees all the MNLF's armed forces, which was meant to disarm as part of the 1996 peace pact but never fully complied.

Hashim said although MNLF leaders had not officially instructed their men to sail to Malaysia, they fully supported the sultan's efforts to reclaim Sabah.

"MNLF fighters are adherents of the sultan, we are followers. So there is more than an alliance," he said. "We feel very strongly against the attacks against our brothers from Sulu."

Malaysian security forces launched a major offensive on yesterday after a three-week standoff with the followers of Sulu sultan Jamalul Kiram III erupted in violence last week that, by the eve of the assault, had left at least 27 people dead.

But the sultan's aides said in Manila that Azzimuddie's group had escaped the attacks, which included air strikes.

The MNLF was founded in the 1960s by Nur Misuari to fight for a Muslim homeland in Mindanao and had once received support from Malaysia.

Meanwhile, Malaysian forces are escalating the hunt for the armed Filipino invaders who dodged a military assault.

NONE Malaysia's police chief Ismail Omar ( left in photo ) said the gunmen had scattered after an air and ground attack and authorities had "expanded the operations area".

He told reporters in Felda Sahabat, a village about 15km from the battleground, the expansion was necessary as invaders were on the move, giving no details, but adding that one gunman was believed killed in an early morning exchange of fire.

However, he declined to answer reporters' questions on whether any of the estimated 100-300 militants had been captured or confirmed dead.

The armed group arrived in Sabah from the adjacent southern Philippines on Feb 9, claiming it for their "sultan" and tearing open a long-dormant territorial row.

After an initial stand-off in the sleepy farming village of Tanduo, two shootouts erupted there and in another town in recent days, which together with related violence has left 19 militants and eight police officers reported dead.

Following the shootings, Malaysia on yesterday launched an attack on Tanduo with jet fighters and soldiers.

'They are eating good food'

But their leader, Jamalul Kiram III, appeared to thumb his nose at Malaysia Wednesday, saying in Manila that he had just chatted by phone with his younger brother, one of the incursion's purported leaders.

NONE "He was telling me they are eating good food, but the hard thing is they are being chased. So where will they go?" he said, declining to specify their location, but adding that they would not surrender.

Kiram, 74, ( left ) is the self-proclaimed heir of the former sultanate of Sulu, which once controlled part of the southern Philippines and claimed sovereignty over Sabah. The intruders are attempting to reassert his authority there.

The news that militants remained on the loose stoked the fears of local residents already on edge over the stunning incursion into their remote corner of Borneo island, which is covered by vast oil palm and other plantations.

"If there are no more negotiations I think more people on both sides will die," local resident Shamsul Bahari said.

"I am scared to even go to work in the palm oil estate."

An AFP reporter saw eight military trucks full of soldiers in full battle gear heading toward Tanduo Wednesday from Felda Sahabat, the nearest point to the trouble-spot that authorities are allowing outsiders to reach.

The trucks were followed by two armoured personnel carriers.

NONE Authorities have not explained how the intruders were able to slip through a security cordon in place for three weeks.

Britain, the United States and Australia issued advisories warning against travel to affected areas.

Some suspect the MNLF orchestrated the offensive because they feared a peace deal being finalised between the Philippine government and another Muslim separatist group would marginalise them.

Philippine presidential spokesman Edwin Lacierda told AFP its navy intercepted 70 people last month trying to join Kiram's followers from the Muslim southern Philippines.

He said the government had no knowledge of Hashim's claim of MNLF fighters on the way.

- AFP