DUBAI, United Arab Emirates (AP) — Rights groups say a prominent activist in the United Arab Emirates has been detained after a lengthy search of his apartment.

Amnesty International says Ahmed Mansoor was detained Monday in the emirate of Ajman after an overnight raid by 12 security officials who confiscated electronic devices and did not inform his wife where he was being taken.

Several rights groups, including Amnesty, are calling for his immediate release.

Mansoor received the prestigious Martin Ennals Award last year for bringing attention to arbitrary arrests, concerns of torture and issues around the independence of the judiciary in the UAE. He's also called for a free press and democratic freedoms in the country ruled by sheikhs.

He was imprisoned in 2011 after being convicted of "insulting officials" and banned from traveling abroad.