The Philippine government on Sunday rejected a call by Muslim guerrillas for a halt in a massive air and ground assault, and instead intensified the four-day attack, capturing a rebel training camp in a southern province, officials said.

Moro Islamic Liberation Front Chairman Al Haj Murad urged the government in a rare news conference Saturday to stop the offensive, warning it could imperil a yearslong peace process and escalate violence in the country's troubled south.

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About 6,000 troops and police commando forces, backed by artillery and bomber aircraft, have attacked guerrilla positions to capture a rebel commander who occupied and looted Christian farming communities in North Cotabato province. Two other commanders are also being hunted who led a rampage last week in which 37 people were shot or hacked to death in Lanao del Norte province.

"There will be no let up in government offensives," Press Secretary Jesus Dureza said.

He said government forces would "enforce the law" if Murad does not turn over the three commanders for justice. Murad has refused to do so.

After four days of air and artillery strikes and attacks by army rangers, rebel resistance has softened, allowing troops to capture a guerrilla training camp in Maguindanao's Mamasapano township, said Army Col. Marlou Salazar, who was overseeing the offensive.

Troops were checking the camp, which has obstacle courses, assembly areas and small buildings for combat training, for possible booby traps and land mines, he said.

"They're scampering and leaving only token forces to delay our advance," Salazar told The Associated Press by telephone.

At least 27 guerrillas have been killed and 21 others wounded in three Maguindanao townships where Salazar's army brigade was pressing its assault against the forces of rebel commander Ameril Umbra Kato. Military and police were continuing a manhunt in nearby Lanao del Norte province for commanders Abdullah Macapaar, also known as Bravo, and Aleem Sulaiman Pangalian.

The National Disaster Coordinating Council reported that at least 40 civilians have been killed and 240,000 displaced by the rebel attacks and the fighting.

"The number keeps growing," Social Welfare Secretary Esperanza Cabral told the AP. "There is fighting that erupts in new places almost every day so more and more are being displaced. So we are hoping that there can be a peaceful resolution very quickly."

Cabral said the World Food Program has increased its emergency rice supplies for refugees from 400 tons last week to 900 tons.

Murad said government troops were attacking the main rebel forces and not only pursuing the three commanders.

The rebels, who have been fighting for Muslim self-rule in the predominantly Roman Catholic nation's south for decades, said they regretted a recent upsurge in violence and that the commanders responsible had acted on their own. Murad said peace talks should resume, but refused to turn over the commanders to face the criminal justice system.

"We cannot subject our members to the laws of the government," Murad said. "We are a revolutionary force."

Just weeks ago, a peace deal to end the decades-long insurgency had seemed within reach after government and rebel negotiators initialed an agreement on an expanded Muslim autonomous region.

But Christian politicians in areas that would be affected challenged the deal in the Supreme Court, triggering the attacks by frustrated rebels.