The alleged mastermind and four other suspects believed to be behind two recent suicide attacks in Pakistan's capital that killed 31 people were arrested by the authorities of the state.
Interior Ministry spokesman Javed Iqbal Cheema said investigators have also identified the two bombers - both Pakistani tribesmen - who blew themselves up in separate attacks in Islamabad last month.
"Fasiullah Khan was the mastermind, planner, and directing the suicide attacks in and around Islamabad," Cheema said at a weekly news conference.
Khan spent six months at the Lal Masjid, or Red Mosque, a radical pro-Taliban mosque in the capital, where he produced 400 petrol bombs, Cheema said, citing investigators.
The Red Mosque and an affiliated Islamic school had started a Taliban-style morality campaign in Islamabad, warning music shops and prostitutes to close their businesses. In July, a military siege and raid against the mosque left more than 100 people dead, including troops and alleged militants.
The suicide bombings appeared to be retaliation for the operation against the mosque, which has been closed since. The seminary was razed after municipal authorities claimed it was built on illegally occupied state land.
The first suicide attack killed 18 people on July 17 at a rally in support of Pakistan's chief justice. Ten days later, another bomber hit a restaurant, killing 13 people, many of them police officers.
Cheema said investigators have identified the two bombers as Yar Mohammed and Khana Din, both from Waziristan, a rugged tribal region bordering Afghanistan and an alleged haven for Taliban- and al-Qaida-linked militants.
Cheema had announced the arrest of two of the five men last week. He did not give any further details about when the five were arrested or say if they had been charged yet.
He did not say whether the bombers or suspects arrested were affiliated with any group.