(Adds details and background)
SANAA, Feb 13 (Reuters) - Attackers fired rocket-propelled grenades at the main prison in Yemen's capital on Thursday in a failed attempt to free inmates, security sources and witnesses said.
Explosions and gunfire between security forces and the attackers could be heard several kilometres away from the prison in northern Sanaa, which has al Qaeda members among its inmates. The biggest explosion rattled windows in the area.
No one claimed responsibility for the attack, but Yemen is grappling with a growing threat from one of al Qaeda's most active wings, which has killed hundreds of people in assaults on state and military facilities in the past two years.
There were no immediate reports of casualties but witnesses saw ambulances driving towards the high-security prison, which police secured after the 30-minute gunfight.
Attackers fired at least one rocket at a police patrol vehicle outside the main prison gates, a police officer at the scene said.
Police sealed off the road to the airport which runs through the neighbourhood where the prison is located, close to the Interior Ministry.
Special forces and armed personnel carriers were being sent in to chase the attackers, a security source said. The attackers failed to enter the prison.
Earlier on Thursday, a British teacher was reported missing in Sanaa in what a Yemeni security source suggested could have been a kidnapping. The abduction of foreigners in Yemen is common.
The U.S. ally, with a population of 25 million, is trying to end nearly three years of political unrest, which began when mass protests erupted in 2011 against Ali Abdullah Saleh, the president of 33 years, who stepped down.
Interim President Abd-Rabbu Mansour Hadi has been facing other challenges in trying to restore stability to Yemen, which shares a long and porous border with top world oil exporter, Saudi Arabia.
Apart from security, Yemen is trying to deal with demands by southern separatists for independence and incorporate rebels from the Shi'ite Muslim Houthi movement, which has been on an offensive to extend its control over the north. (Reporting by Khaled Abdullah; Writing by Sylvia Westall; Editing by Andrew Roche)
Our Standards: The Thomson Reuters Trust Principles.