The heart-wrenching last moments of American hostage Guillermo Sobero before his beheading have been revealed by a captured Abu Sayyaf militant yesterday, who admitted witnessing the beheading by former colleagues in the extremist group which continues to hold on to eight Filipino and an American couple in southern Basilan's jungles.

Police presented to reporters Bashir Balahim, 16, one of four Abu Sayyaf members captured in separate arrests in the province of Basilan and in Zamboanga City.

The militants earlier announced having executed Sobero on June 12 as a gift to President Gloria Macapagal-Arroyo after she rejected an Abu Sayyaf demand to allow Malaysia to negotiate for the safe release of the foreigner.

Bashir claimed militant leader, Abu Sabaya, ordered Sobero killed after President Arroyo rejected their demand.

"Sobero was pleading for his life and he was crying and trembling in fear," he told reporters. He added that the American was crying, 'please...please I beg you...please...no...' and then his head fell to the ground, with his body still shaking."

"Sobero was blindfolded and his hands were tied behind his back when executed," Bashir noted. "A heavy machete was used in decapitating Sobero."

He named his companion, Abu Haija, as the one who executed Sobero.

Bashir's father, Abdul Balahim, tried to prevent his son from talking to reporters about the execution, but he was ignored.

Bashir said he was one of those guarding the two remaining American hostages in Basilan's jungle near Lantawan town, but he had been captured by policemen.

"I and my father were among those who closely guarded Martin and Gracia (Burnham), and the hostages are okay," he claimed.

Senior Supt Damming Unga, commander of the Mindanao Police Task Force, said Bashir was captured with his father, Abdul, 48, a leader of an Abu Sayyaf unit, in Basilan's Tuburan town.

A third militant sub-leader, Faizal Abbas, was captured by policemen and members of the National Bureau of Investigation (NBI) in a remote village in Zamboanga City on Tuesday night.