Security forces in the Philippines have captured 40 of the 158 inmates who escaped from a prison in the country's south, in a brazen jailbreak blamed on Muslim rebels.

Prison authorities said on Thursday that 111 inmates remained on the run in remote farmlands and isolated villages, while seven others had been killed in the manhunt.

"This is a very wide area. Aside from sugar, rubber and coconut plantations, there are areas and camps held by rebels that we cannot easily enter," prison warden Peter Bongngat told the AFP news agency.

On Wednesday, more than 100 gunmen facilitated what officials say was the biggest jailbreak in the country's history.

The attack on the North Cotabato District Jail in Kidapawan, some 930km southeast of the capital, Manila, took place in a region where Muslim rebels have been active for generations.

Al Jazeera's Jamela Alindogan, reporting from Kidapawan, said it was still unclear who orchestrated the jailbreak.

Officials suspect the commander of the Moro Islamic Liberation Front (MILF), a group that is undertaking peace negotiations with the Philippine government, or another rebel group, the Bangsamoro Islamic Freedom Fighters (BIFF).

The two groups, however, have denied any involvement.

The BIFF is a small group fighting for an independent Muslim state in southern Philippines. It has carried out several attacks in recent years in an effort to derail the peace process.

MILF spokesman Von al-Haq insisted on Thursday that none of its members was involved in the raid, adding that the group was willing to coordinate with the government to allow searches in its communities.

"Kidapawan city is one of the most progressive cities in Mindanao province but it has long been caught up in the violence that has scaled back this region for decades," our correspondent said.

Separatist violence has raged since the 1970s in Mindanao, the main southern Philippine island. It is home to most of the country's five million Muslims, but Christians remain the overall majority.