Four majors serving in the Pakistan army are being questioned over links to the banned Islamist group, Hizb-ut-Tahrir.
The development followed an announcement on Tuesday that a brigadier had been arrested and was being interrogated over his alleged links to the organisation.
Brigadier Ali Khan, who was detained last month, was the highest-ranking serving officer to be arrested in a decade.
His family has said they have not heard from him for weeks. They insist that he is innocent of the allegations.Reuse content