SANAA, Jan 19 (Reuters) - Yemen offered a 15 million Yemeni rial (around $75,000) reward on Saturday for information leading to the capture of gunmen who killed two Belgian tourists and their two Yemeni drivers, a security official said.

Friday's attack came less than a week after al Qaeda's wing in Yemen vowed to carry out unspecified operations to win the release of jailed Islamic militants.

Yemeni officials have not ruled out al Qaeda involvement in the attack and are searching for the attackers though no one has claimed responsibility for the shooting near the eastern city of Shibam, famous for its old towers, in the Hadramout region.

"We do not dismiss al Qaeda's involvement, considering the style of the attack and the group's frequent threats against foreign interests in the region," a government official said.

In July, a suicide bombing killed seven Spanish tourists and wounded six at the Queen of Sheba Temple.

Yemen, which joined the U.S.-led war on terrorism after al Qaeda's Sept. 11, 2001 attacks on U.S. cities, has often been the site of militant attacks and kidnappings by disgruntled tribesmen.

The ancestral home of al Qaeda leader Osama bin Laden, Yemen is viewed in the West as a haven for Islamic militants.

"We don't have any information as far as the involvement of Islamists but one can note that the province of Hadramout is known for its Islamism and groups of extremists," Belgian Foreign Minister Karel De Gucht told Reuters on Friday.

In an Internet posting last week, al Qaeda's wing in Yemen vowed to free its prisoners from the country's jails and retaliate for the killings of militants by the government. Officials said last year that July's attack had been preceded by an al Qaeda demand for the release of jailed comrades.

Dozens of al Qaeda militants are serving jail terms in the country on the Arabian Peninsula for involvement in bombings of Western targets and clashes with the authorities.

One of the poorest countries outside Africa, Yemen has been trying to attract tourists put off by kidnappings and bomb attacks and boost foreign investment as its oil dwindles. (Reporting by Mohammed Sudam, Writing by Lin Noueihed)

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