MANILA, Philippines -- Detained Indanan, Sulu Mayor Alvarez Isnaji and his son, Haider, will not be allowed to vote in Monday’s Autonomous Region in Muslim Mindanao (ARMM), police said on Monday.

Isnaji, a candidate for ARMM governor, and his son are detained at the Custodial Center in Camp Crame, Quezon City, and have been charged for allegedly masterminding the June kidnapping of a television news team and their university professor guide in Sulu.

The two have denied involvement in the abduction.

The Philippine National Police has also tightened security at Camp Crame, Director General Avelino Razon Jr. said. He added that not allowing the Isnajis to vote is part of their security measures.

"He cannot vote. We have also heightened our security in the camp and others camps in the Philippines in connection with the ARMM election," Razon said in an interview.

The ABS-CBN news team of reporter Ces Drilon and two cameraman, and their guide Professor Octavio Dinampo, were kidnapped by alleged members of the Abu Sayyaf in early June and released nine days later after the payment of a ransom authorities say could have been as much as P20 million.

Police claim Isnaji, who acted as chief negotiator during the hostage crisis, and his son pocketed P3 million of an initial P5-million payment to the kidnappers.