(Adds more attacks in Sanaa and central Yemen)
SANAA, May 9 (Reuters) - Yemen's defence minister escaped an assassination attempt by suspected al Qaeda militants in southern Yemen on Friday, a security source told Reuters.
The source said Muhammad Nasir Ahmad and a number of senior security officials were attacked by gunmen while travelling in their vehicles in the province of Shabwa.
"They opened fire on the convoy, but no one was killed or wounded, the minister is safe," said the source. No immediate claim was made for the attack.
In a separate incident, four Yemeni soldiers were killed and three wounded in an ambush by suspected al Qaeda fighters in the central Yemeni province of al-Bayda, local tribal sources told Reuters.
Al Qaeda holds the defence minister responsible for a military campaign that has driven it from its strongholds in southern Yemen, an area that Washington considers one of the main battlefields in its global campaign against Islamist militants.
The minister had survived at least five assassination attempts since December 2011, when a new government was formed after a power transfer deal under which veteran president Ali Abdullah Saleh stepped down.
The soldiers were killed as the army was shelling areas where it believed al Qaeda militants were sheltering, the tribal sources said.
The Interior Ministry said al Qaeda militants had been fleeing to the provinces of Maarib and al-Bayda after being driven out of their strongholds in Abyan and Shabwa.
The government's offensive in the south is its most concerted campaign against al Qaeda in the Arabian Peninsula (AQAP) in nearly two years. The group has been blamed for deadly attacks against security forces, foreigners and oil and gas facilities.
In the capital Sanaa, 11 soldiers were wounded when an explosive device was set off in a neighbourhood east of the capital.
"The device exploded as a vehicle belonging to special security forces passed by," a police source said.
"We think it is an attempt by terrorist elements to respond to the defeat in the provinces of Abyan and Shabwa."
Western powers including the United States are keen to prevent any spillover of violence into neighbouring oil power Saudi Arabia and to stop Yemen being used as a springboard to attack Western targets.
(Reporting by Mohamed Ghobari; Editing by Amena Bakr and John Stonestreet)