Another suspect had been arrested for alleged involvement in killing of Pakistan People's Party (PPP) Chairperson and former Prime Minister Benazir Bhutto on Dec. 27, officials said.
The suspected had been detained along with Aitezaz Shah, a 15-year teenager, whose arrest was announced earlier, have been sent to Islamabad from Dera Ismail Khan for further queries.
More arrests are expected based on initial investigation and efforts are being made to trace the contacts of suspects with Baitullah Mehsud, the Associated Press of Pakistan (APP) reported quoting the ARY One World, a Dubai-based Pakistani news channel.
The arrests in connection with Benazir's assassination had been made and investigations are continuing, Interior Secretary Syed Kamal Shah confirmed on Sunday.
Shah told media that they are looking into all aspects and they are not saying anything unless it is corroborated through investigations.
Benazir was killed in a gun and suicide bomb attack at an election rally in Rawalpindi.