Yemeni authorities have arrested dozens of people with suspected links to al-Qaeda since Monday's suicide bombing that killed seven Spanish tourists and two Yemeni.
President Ali Abdullah Saleh and other senior officials have said they believe al-Qaeda was behind the car bomb suicide attack at the Queen of Sheba Temple in the Marib province, about 150 kilometres east of the capital.
Mr Saleh, whose country joined the US-led war on terrorism after the September 11th attacks, offered a $75,500 reward for information leading to the capture of militants behind the attack.
Security sources have said al-Qaeda issued a statement last week demanding the release of some of its members jailed in Yemen, which has been battling Islamist militant for years, and threatening to take unspecified action.
A security source said on Monday that the bomber may be one of 13 convicted al-Qaeda members who escaped from prison in 2006.
Yemen is the ancestral home of al-Qaeda leader Osama bin Laden.