A close aide of senior al-Qaeda-linked Abu Sayyaf leaders has been arrested in a southern Philippine city, a navy spokesman said Thursday.

The suspect, Usman Asari Aldani, was arrested Monday in the public market of Isabela City in Basilan province, 900 kilometres south of Manila, Marine Lieutenant Colonel Edgard Arevalo said.

Arevalo said the suspect was a bodyguard to slain Abu Sayyaf chieftain Khadafi Janjalani and his successor, Isnilon Hapilon, who has continued to elude arrest.

Aldani has a 2-million-peso (45,558-dollar) bounty on his head and has been the subject of several arrest warrants for his involvement in terrorist attacks and kidnappings by the Abu Sayyaf.

The military has been conducting an offensive against Abu Sayyaf rebels, who have been blamed for some of the worst terrorist attacks and high-profile kidnapping-for-ransom incidents in the country.