Dozens of suspected Islamic militants broke through a concrete wall and barged into a jail in the volatile southern Philippines on Sunday, freeing 31 inmates in a nighttime attack that sparked a gun battle in which two people were killed, officials said.

Al Rasheed Sakalahul, vice-governor of Basilan island, said about 30 heavily armed men cut through padlocks with bolt cutters after destroying the wall at the provincial jail in Isabela city to free several detained Muslim guerrillas, adding that other inmates also dashed to freedom.

The daring assault sparked a brief clash that killed one attacker and a jail guard, he said. At least 31 inmates escaped, including suspected militants from the Moro Islamic Liberation Front, a large Muslim rebel group engaged in peace talks with the government, and the smaller but more violent Abu Sayyaf group, which has been linked to al-Qaeda, regional military commander Maj. Gen. Benjamin Dolorfino said.

Government troops and police were pursuing the attackers and the escaped inmates, he said. It was the latest violence in the southern Mindanao region, scene of a decades-long Muslim separatist rebellion.

The attack occurred hours before Defence Secretary Norberto Gonzales and military chief of staff Gen. Victor Ibrado flew to Basilan, a predominantly Muslim island 880 kilometres south of Manila, to meet Roman Catholic church leaders who have appealed for martial law to be declared in the province amid recent kidnappings blamed on Islamic militants and the beheading of one hostage.

President Gloria Macapagal Arroyo imposed martial law in nearby Maguindanao province last week to allow troops to crack down on a powerful political clan blamed for the massacre of 57 people, including 30 journalists, on Nov. 23.

Arroyo lifted martial law in Maguindanao on Saturday but the province remains under a state of emergency.