Tribesmen allied with al-Qaida's branch in Yemen have imposed a ban on the nation's widely popular plant called qat, which is a mild narcotic, in a southern city overrun by the militants last month.

Yemeni men traditionally chew qat from around midday, stuffing their mouths with the leaves of the plant and letting its narcotic dissolve in their saliva.

Leaflets from the tribesmen organized as "Sons of Hadramawt" have been distributed across Mukalla, the capital of Yemen's largest province, Hadramawt, which was seized by al-Qaida in April.

The flyers say qat chewing is banned as of Thursday and that violators will face a "religious responsibility," without elaborating.

Much of the agriculture in this impoverished Arab Peninsula nation — and 30 percent of its water — has been diverted into cultivating qat.