* Impoverished Yemen battling al Qaeda, separatists
* Witnesses say at least six killed, 26 wounded (Updates with lower death toll from state news agency, background, detail)
By Mohammed Ghobari
SANAA, Aug 25 (Reuters) - A bomb ripped through the side of a bus carrying Yemeni air force personnel to their base in the capital Sanaa on Sunday, killing at least one officer and wounding several others, state media reported.
Witnesses told Reuters as many as six people died when the device, planted on the vehicle, exploded, blowing passengers' bodies into the street.
The impoverished country next to the world's top oil exporter Saudi Arabia is battling a number of armed groups, including al Qaeda fighters, who Washington said this month could be planning attacks.
Yemen's security personnel have been targeted by Islamist militants though most of the attacks have taken place in the largely lawless south and east.
"This cowardly terrorist act resulted in the martyrdom of one person and injured a number of others, several of whom are in a serious condition. They have all been transferred to hospital," the air force's spokesman told Saba news agency.
It named the dead man as Sergeant Mohammed al-Shaghdari.
Air force officer Ameen Saree, who was among the first to reach the scene, earlier said the blast killed at least six people and wounded 26.
There was no immediate claim of responsibility.
Yemen has been gripped by turmoil since pro-democracy protests against former President Ali Abdullah Saleh broke out in early 2011.
Suspected al Qaeda militants killed four Yemeni soldiers during an attack on forces guarding the country's only liquefied natural gas (LNG) export terminal in the southern Shabwa province on August 11.
A suicide bomber in an army uniform killed more than 90 soldiers rehearsing for a parade in the heart of Sanaa in May last year.
Earlier this month, Yemeni authorities said that had thwarted a plot by al Qaeda to seize two major oil and gas export terminals and a city in the east of the country.
The United States and other Western powers shut their diplomatic missions across the Middle East, Africa and Asia after Washington said it had information about unspecified terrorist threats. Many later re-opened. (Additional reporting by Khaled Abdullah; Writing by Mahmoud Habboush, Editing by Yara Bayoumy and Andrew Heavens)