The bus bombing is the latest incident in a long history of violence in southern Philippines [EPA]

Security forces in southern Philippines have arrested five suspects in connection with a bus bombing last week that killed at least 10 people and wounded nine others.

An army spokesman said four of the suspects were captured on Saturday in a raid in Cotabato city on the southern island of Mindanao.

A 15-year-old boy who was arrested earlier had provided information that led to the arrest of his alleged accomplices, Lieutenant-Colonel Benjamin Hao, the regional army spokesman, said.

The bus was travelling with 50 passengers on board on Thursday when a bomb struck the vehicle in Matalam township in North Cotabato province.

The five suspects were being questioned, and it was unclear whether they were affiliated with any of several Muslim armed groups that were initially blamed for the attack.

Officials earlier said the bus company had received extortion demands from armed groups in the in the area, which is a known stronghold of the separatist Moro Islamic Liberation Front (Milf) and other gangs.

The Milf has denied involvement in the bus attack, but police and military officials say many of its former members were known to be working alongside armed extortionists targeting businessmen in the country’s south.

Officials investigating the bombing have not ruled out involvement of the Abu Sayyaf group, which is said to have links to al-Qaeda and also operates in the south.

Separatists in southern Philippines have been fighting for an independent homeland for decades. The region is also home to criminal gangs.

In April last year, two home-made bombs exploded hours apart on a bus in the same region, wounding the conductor and five passengers.

A bomb exploded at a Cotabato city bus terminal in February the same year, wounding two people.

Source: Agencies