The action against the militants' supporters in the country was started following the ongoing military offensive in the North Waziristan tribal region against local and foreign insurgents.
A police official said that most of the arrests were made in province of Punjab, where more than 300 people were nabbed.
The maximum arrests within Punjab were made from Bahawalpur district, where Jaish-e-Mohammed terror group of Maulana Masood Azhar is based.
Azhar was one of the three terrorists who were released in exchange for the passengers of Indian Airlines Flight 814 that was hijacked to Kandahar in 1999.
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The authorities also arrested 150 people from Balochistan and Khyber-Pakhtunkhwa provinces.
An official of interior ministry said that those arrested will be prosecuted under recently passed Protection of Pakistan Act under which police can hold an accused for 60 days without trial.
Under the controversial law, the security forces have also been empowered to shoot a person at sight.
Several extremist and militant groups are active in Pakistan and authorities fear a backlash in the cities after the North Waziristan operation.