PESHAWAR, Pakistan (Reuters) - A pilotless U.S. drone was suspected to have fired a missile into a Pakistani area on the Afghan border on Tuesday, but there was no word on the target or casualties, a government official said.

The missile was thought to have been fired into the Mohmand ethnic Pashtun tribal area in northwest Pakistan where this year, U.S.-controlled Predator aircraft have struck at least four sites used by al Qaeda operatives, killing dozens of suspected militants.

“There was an attack by a spy plane close to the Afghan border but we don’t have information about casualties or damage,” said the government official based in the region. He declined to be identified.

Mohmand has not been a hotbed of support for al Qaeda and the Taliban but militants are known to operate there.

A Pakistani military spokesman said there had been a clash in the area but on the Afghan side of the border, where Afghan forces had been battling militants.

Neither U.S. nor Pakistani authorities usually confirm U.S. missile attacks on Pakistani territory, which would be an infringement of Pakistani sovereignty.