Police in the southern Pakistani city of Karachi say they have arrested two doctors allegedly involved in planning terrorist attacks.
A victim of the 10 June attack in Karachi blamed on Jundallah
The brothers, Akmal Waheed and Arshad Waheed, had been missing since the middle of last month.
Police say they have been detained on suspicion of close links with a little-known organisation called Jundullah (Army of Allah).
Family members deny the men are involved in any terrorist activity.
The family had blamed security agencies for the men's disappearance.
Police initially denied they were holding the men but a senior Pakistani police official, Tariq Jameel, has now confirmed the detentions.
He said they had been arrested on Friday.
The police have arrested nine others allegedly belonging to Jundullah.
They are suspected of killing 11 people during an abortive attempt on the life of Karachi's army commander,
Lieutenant-General Ahsan Saleem Hayat, on 10 June.