An advance party composed of six American servicemen arrived in Zamboanga City yesterday ahead of U.S. anti-terrorism experts as senior Philippine security officials flew to southern Basilan island to assess the ongoing rescue operation on two Americans and eight Filipinos held by Abu Sayyaf group, officials said.

"An advance U.S. military party arrived here and foreign military attaches and other officials are expected to be here on Wednesday to make a courtesy call to (Southern Command chief) Lt. Gen. Roy Cimatu," a regional military spokesman Lt. Col. Darwin Guerra said, but declined to give more details.

The local Air Transportation Office said a U.S. Air Force cargo plane carrying the foreigners arrived shortly before 9 a.m.

A security official at the Philippine Air Force Edwin Andrews Air Base said he saw at least five U.S. military experts disembark from the plane, but refused to identify the Americans.

The official, who spoke on condition of anonymity, said the five Americans met with senior army officers inside the base and had been briefed about the security situation in Basilan and Zamboanga City.

U.S. Embassy Charge d'Affaires, Robert Fitts, said at least 26 U.S. military experts arrived in Manila and would meet Philippine security officials to discuss the ongoing government efforts to free the American hostages – Martin and Gracia Burnham, held since May 27 by the Abu Sayyaf.

Fitts said the U.S. anti-terrorist experts will consult the Philippine military on what type of training and equipment it needs to fight the Abu Sayyaf.

He said the Americans will not join troops in combat operations. "They are consultants and not combatants," he said.

Philippine military spokesman Brig. Gen. Edilberto Adan said the troops in Basilan need helicopters and patrol boats.