Manila  - Philippine troops foiled Tuesday a roadside bombing in a southern province when they found three homemade bombs during a routine patrol, a regional military spokesman said.

The devices were planted along a road in Sirawai town in Zamboanga Del Norte province, 870 kilometres south of Manila, Major David Hontiveros said.

Hontiveros said soldiers were on their regular security patrol when they spotted the bombs, which were later disarmed. The devices were made from 22 litres of ammonium nitrate.

"Our troops have thwarted another attempt by terrorists to conduct further bombings," he said, adding that investigators were still trying to determine who was behind the foiled bombing.

Various armed groups operate in the province, including the separatist Moro Islamic Liberation Front (MILF) and the al-Qaeda-linked Abu Sayyaf group.

While the MILF has officially denounced terrorism in the fight for an independent Islamic state in the southern region of Mindanao, some rogue members have been involved in terrorist attacks.

The Abu Sayyaf has been blamed for some of the worst terrorist attacks in the Philippines as well as high-profile kidnappings involving foreign hostages. (dpa)