At least 13 militants were killed Sunday when Pakistani security forces' gunship helicopters charged at their hideouts in the country's tribal area of Orakzai, according to local TV reports.

Six militants were injured in the air attack, said the reports.

Meanwhile, at least six militants were killed Sunday as Pakistani security forces pounded at their hideouts in the neighboring Kurram agency.

Orakzai has a large number of presence of local, al-Qaida and foreign militants. Militants fled to this area months ago before the military operation was started in South Waziristan.

Orakzai is bounded by Kurram agency in the west, Khyber in the north, Kohat District on the south and Peshawar in the east.

Orakzai is the second smallest in area after Bajaur Agency out of the seven Federally Administered Tribal Areas (FATA) of Pakistan. It is also the only FATA agency which is not bordering Afghanistan.