The military fought a day-long battle with the rebels
Father Cirilo Nacorda, based on the southern island of Basilan, narrowly escaped being kidnapped by the group in June.
He has alleged that an army general and four other senior officers deliberately allowed the kidnappers to escape past a military cordon on the island in exchange for money.
He told a House of Representatives investigating committee on Friday that among his sources of information was an army captain who has agreed to testify on the alleged collusion.
The priest spoke only briefly to the committee, which is holding the inquiry in Lamitan town on Basilan, where June's incident took place. Several hundred supporters gathered outside to cheer him on.
The Abu Sayyaf raided the town's hospital and church complex on the night of 1 June, taking with them most of the American and Filipino hostages seized from a luxury resort a few days earlier.
The raid
Soldiers surrounded the hospital and opened fire, but the kidnappers escaped through a back door with most of the hostages. The military has said the rebels used hostages as shields to stop the soldiers shooting at them.
Father Nacorda alleges that the officers, led by Brigadier General Romeo Dominguez, received a payoff to let the rebels go. He said a guerrilla leader negotiated with the officers using a mobile phone.
The general has denied the charges.
He told local radio on Friday that the rebels could not have arranged bribes by mobile phone because there is no reception in the area.
Last week Abu Sayyaf leader and spokesman Abu Sabaya phoned a local radio station and said he had paid the soldiers.
The Abu Sayyaf say they are fighting for independence for the Muslim minority in the south of the mainly Christian Philippines, but the government says they are nothing but criminals.
Among the 20 hostages still being held are American missionaries Martin and Gracia Burnham. The rebels say they have beheaded a third American, Guillermo Sobero, but his body has not been found.
About 5,000 soldiers have been trying to catch the kidnappers without success.
There have been growing accusations from the press and public that the military is secretly working with the rebels for a share of the ransom, or are simply incompetent.