ADEN, Yemen, Nov 22 (Reuters) - Authorities on Yemen's Socotra island burnt two tonnes of the mild narcotic drug qat on Saturday, a shipment seized from smugglers trying to defy last week's ban by the archipelago's governor, local officials said. Yemenis have chewed qat for centuries and although widespread, its use is seen as a social ill by some, sapping productivity and finances. Sessions begin in the afternoon and can last long into the night. The national pastime has survived the last few years of turmoil in the impoverished Arab country, including the war that began last year involving air and ground troops from an Arab coalition led by Saudi Arabia. It is not uncommon to see Yemeni fighters and soldiers with a wad of qat leaves in their cheeks.

But last week the governor of Socotra, a sparsely populated island renowned for its exotic wildlife, sought to stamp out the habit by banning the import or chewing of qat.

According to Yemeni media, Saeed Ba Huqaiba introduced to the ban due to the health risks and financial consequences of qat use.

Local officials said on Saturday they had intercepted and burnt a shipment of two tonnes of qat smuggled from the Hadramout province on the Yemeni mainland.

Qat is classified by the World Health Organization as a "drug of abuse that can produce mild to moderate psychological dependence". Its physical symptoms can include hallucinations, depression and tooth decay.

Past surveys in Yemen suggest at least 80 percent of men, about 60 percent of women and increasing numbers of children under 10 - settle down most afternoons to chew.

(Reporting by Mohammed Mukhashaf, writing by Sami Aboudi; Editing by Raissa Kasolowsky) ((Sami.Aboudi@thomsonreuters.com; +97143918301;))