However, Senator Richard Gordon, the head of the Philippine National Red Cross, refused to say who may have been responsible.
"It is my hope that these people realise that the Red Cross is there to help them. The Red Cross is neutral," he told the Associated Press.
"It is my hope that these people realise that the Red Cross is there to help them. The Red Cross is neutral"
Richard Gordon, chairman of the Philippine National Red Cross.
Philippine military officials identified the kidnapped workers as Andreas Notter, a Swiss national, Eugenio Vagni, from Italy and Jean Lacaba, a Filipino national.
Jolo, a majority Muslim island about 950km south of Manila, was once portrayed as a success story in the Philippine military's battle to flush out the Abu Sayyaf but the group has since resumed kidnappings and decapitations.
The military's relations with the locals have deteriorated due to operations that have forced villagers from their homes.
Despite American military training and assistance, including dozens of US troops stationed in Jolo, Abu Sayyaf fighters have staged several kidnappings on Jolo and nearby Basilan island in recent months, although to date all the abductees have been released, usually after a ransom has been paid.
Philippine officials have said they believe the group are resorting to ransom kidnappings because they are running out of funds.
In 2002, Abu Sayyaf fighters kidnapped nearly two dozen people from a resort, including three Americans.
One was beheaded and the other was killed during a military rescue operation.
The incident prompted Washington to deploy US troops to the southern Philippines, but they are barred from combat operations.