Pakistani police arrested on Tuesday a suspected Islamic militant accused of training religious students to become suicide bombers, a police official said.
In a separate incident, a security official said 29 suspected Taliban fighters from Afghanistan had been arrested in a raid on a hospital in southwestern Pakistan, where they were getting treatment after being brought from Afghanistan.
The suspected suicide-bomb trainer, Mohammad Ashraf Qureshi, was arrested with two other men in a pre-dawn raid in the city of Karachi, senior police official Chaudhry Aamir Hameed said.
"He's been targeting young boys in madrasas, brain-washing them and turning them into suicide bombers," Hameed said, referring to Islamic schools, some of which have earned reputations for being militant breeding grounds.
Qureshi was involved in preparing suicide bombers for the killing of prominent Shi'ite Muslim cleric Allama Hassan Turabi in Karachi last month, Hameed said.
Police identified the suicide bomber who killed Turabi as 16-year-old Abdul Karim. The July 14 attack outside Turabi's home, which also killed one of his nephews, sparked violent demonstrations in Karachi.
Qureshi was also known to have visited neighbouring Afghanistan, which has been hit by a wave of suicide bombings in recent months, though it was not known if he had organised attacks there, Hameed said.
Qureshi's interrogation was still going on, Hameed said.
Another senior security official said the 29 Taliban had been arrested in a raid on a hospital in the southwestern city of Quetta this week.
"Some of them are wounded and we are interrogating them," said the official, who declined to be identified.
Afghanistan has long said the Taliban were getting support from Pakistan, and has repeatedly called on Pakistani authorities to do more to cut off help for the insurgents.