"An army unit raided the house of Ali Zayd Ismail, wanted on several counts of drug trafficking in the area of Al-Hamudiya-Brital," in the eastern Bekaa Valley, the army said.

"The unit was shot at... forcing the force's members to retaliate, which led to the killing of eight gunmen," it said in a statement.

The army said it detained a further 41 people, six of whom were wounded in the clashes, and seized weapons and drugs.

The statement did not say whether Ismail, a notorious figure, was among those killed or arrested.

But an army source told AFP he was killed in the raid and identified by a relative.

In April, the army seized 20 kilogrammes (44 pounds) of Captagon from an abandoned house they said Ismail was using in Brital.

Captagon is classified by the UN Office on Drugs and Crime as an "amphetamine-type stimulant" and usually blends amphetamines, caffeine and other substances.

And in December, the army seized 800 kilogrammes of cannabis from Ismail's home.

Consuming, growing and selling marijuana are all illegal in Lebanon.

But in the Bekaa Valley, long marginalised by the central government, its widespread production has become a multi-million-dollar industry.

The Lebanese parliament is soon to review legislation to legalise medicinal marijuana, its speaker Nabih Berri said last week.

The move comes after a consulting firm, charged with setting a vision to kickstart the Lebanese economy, suggested legalising and regularising the production and sale of marijuana.