The Philippines police and military are on heightened alert, following threats of retaliatory attacks by the Abu Sayyaf rebel group after several of its members were killed in a prison revolt. The 29-hour uprising at a high security prison in the capital, Manila, began on Monday when a group of inmates overpowered the guards and holed themselves up in the building. During an operation to end the uprising, police shot dead 22 inmates, including three Abu Sayyaf leaders.Our correspondent in Manila, Shirley Escalante, says Abu Sayyaf spokesman, Abu Solaiman, has warned the group will carry out bolder and wider attacks than in the past. The spokesman says the Abu Sayyaf leaders who died in the prison revolt acted on orders from the group's leaders in the jungles. The prison's warden and five other jail officers have been relieved from their posts, as an investigation into the revolt gets underway.