MANILA, Philippines -- Government troops plan to intensify US-backed assaults on three southern provinces to finish off the Abu Sayyaf and prevent it from retaliating with bomb attacks after the death of its top leader, the military chief said Sunday.

The Philippine government announced on Saturday that Abu Sayyaf chieftain Khadaffy Janjalani, was killed in a clash with troops four months ago, citing results from DNA testing done in the United States.

The announcement came four days after US-backed Philippine troops killed senior Abu Sayyaf commander Abu Solaiman, one of Janjalani's possible successors.

'The tempo of our offensives now would be faster and more ferocious,' Armed Forces chief of staff General Hermogenes Esperon Jr. told The Associated Press in a telephone interview.

'We'll give them no quarters, we have to hit all the remaining leaders while they're in a crisis,' Esperon said.

In a sign of the troops' high morale, Esperon said he recently allowed some of the 7,000 soldiers pursuing Abu Sayyaf's remaining guerrillas on Jolo island to take a break from the military campaign that began August 1 but virtually nobody took the offer.

'They can feel that the final battles are at hand and they want to be part of those final battles,' Esperon said.

The deaths of Janjalani and Sulaiman, who oversaw Abu Sayyaf's battles and logistics, has considerably weakened the insurgents on the battlefield, he said quoting information based on the most recent battle assessments.

'Their volume of fire has really become weak and they've lost their capability to rapidly maneuver after they lost their leaders,' he said.

Aside from stepping up assaults against the Abu Sayyaf on Jolo, about 950 kilometers (600 miles) south of Manila, a Marine contingent would be deployed to nearby Basilan province to help hunt Abu Sayyaf remnants there and undertake humanitarian projects, Esperon said.

There will also be operations in nearby Tawi Tawi province, where the Abu Sayyaf has staged attacks.

Government troops would focus on hitting the groups of remaining Abu Sayyaf leaders Radulan Sahiron and Isnilon Hapilon, two of the likely successor to Janjalani, and more than 300 rebels fighting with top Indonesian terror suspects Dulmatin and Umar Patek, who are believed to still be on Jolo, Esperon said.

Dulmatin and Patek are blamed for the 2002 bombings in Bali, Indonesia that killed 202 people, and also have provided bomb-making training to Indonesian and Filipino Muslim extremists.

Janjalani's death was confirmed after DNA tests in the US compared tissue samples taken from remains found buried last month in the jungles near Jolo's Patikul town with those of Janjalani's imprisoned brother. Janjalani was apparently wounded in a September 4 clash with troops and later died, the military said.

The US Embassy, which offered a US$5 million (€3.86 million) bounty for Janjalani for a series of attacks on Americans, said his death marks 'an important and positive step forward in the ultimate goal of eliminating the ruthless and dangerous Abu Sayyaf group, and in destroying its links with international terrorist groups' such as Indonesian-based Jemaah Islamiyah.

US forces have provided combat training and weapons, including night-vision goggles, to Filipino troops battling the Abu Sayyaf. They have also helped track down militants with high-tech surveillance equipment but have not engaged in direct combat, the Philippine military says.

Janjalani and his key commanders have been accused of several deadly attacks in the Philippines, including a 2004 bombing that gutted a ferry, killing 116 people in one of Southeast Asia's worst terrorist strikes.

They also carried out mass kidnappings, including the abduction of 17 Filipinos and three American tourists -- missionary couple Martin and Gracia Burnham and Guillermo Sobero -- from Palawan province in May 2001.

Sobero was beheaded by the militants and Martin was killed during a military rescue in June 2002 in which his wife was wounded.