Yemen has battled a wave of al Qaeda attacks over the past year, as well as secessionist sentiment in the south which led to clashes this week that provoked a rare call by the U.S. embassy for the parties to act to keep Yemen united.

The court said the four men -- Tawfik Ali al-Faqih, Muadh Ali al-Zuroud, Nabil Ali al-Suraihi and Ismail Ali Hizam Ghorab -- formed a group planning to attack tourists, government buildings, security forces and foreign interests.

Three of the men were sentenced to three years in jail and the fourth, Ghorab, to two and half years. They were arrested in 2008. They plan to appeal the verdict.

Sanaa also faces a Zaydi Shi'ite rebellion in the north and rebellious tribes who reject central authority, forming fertile ground for militants opposed to President Ali Abdullah Saleh's cooperation with U.S. anti-terror efforts to operate.

Neighbouring Saudi Arabia, the world's largest oil exporter, has said it fears instability in Yemen could allow it to become a launch pad for a revival of a 2003-2006 campaign by al Qaeda militants to topple the U.S.-allied ruling Al Saud family.

Source: Reuters