Pakistani security agencies have arrested Mursaleen, a top terrorist, in connection with the Marriott Hotel suicide attack.
Mursaleen is Al Qaeda's number two Ayman al-Zawahiri's close aide.
According to a channel, Mursaleen was arrested from a mosque in Gujranwala on Sunday, where he was living under the name of Jamshed. He was later taken to Islambad for interrogation.
Mursaleen was an important leader of the banned anti-Shiite militant organisation Lashkar-e-Jhangvi, and his arrest carried a reward of Rs 5 crore.
He was also on the US Federal Bureau of Investigation's list of most wanted people, the channel added.
Mursaleen masterminded several acts of terrorism, including attacks on former president Pervez Musharraf in Rawalpindi and Shiite leader, Allama Hassan Turrabi in Karachi.