Yemeni Defence Minister Mohammed Nasser Ahmed survived a car bomb that hit his convoy on Tuesday killing 12 people, a day after the army announced killing Al-Qaeda's branch number two.
More than 200,000 Yemenis, meanwhile, rallied in the capital demanding the repeal of an immunity granted to former president Ali Abdullah Saleh under a Gulf-brokered deal that eased him out of power in February.
The defence minister "escaped an assassination attempt using a bomb-laden car that targeted his convoy... as he was leaving a weekly cabinet meeting," state news agency Saba reported.
The defence ministry news website 26sep.net quoted Interior Minister Abdelqader Qahtan as saying that the attack left "12 people dead, including seven of the defence minister's guards."
Twelve people were also wounded, "some of them seriously," in the "terrorist attack," Qahtan said.
The blast damaged several cars and left a nearby house on fire, Qahtan said, adding that he has ordered a probe.
A security official had earlier told AFP that the car exploded near the vehicle carrying guards, killing seven of them.
One security official said he saw "four charred bodies being pulled out of the wreckage."
Smoke billowed from the area of the explosion sealed off by police while ambulances rushed to the scene which hosts several government departments as well as security headquarters, witnesses said.
The attack comes a day after 26sep.net said that second in command of Al-Qaeda in the Arabian Peninsula (AQAP), Saeed al-Shehri, was killed in an army operation in the country's east.
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No party has, however, yet claimed responsibility for the bomb.
In May, AQAP claimed responsibility for a suicide attack in the capital in which nearly 100 soldiers were killed, saying Ahmed was the target, condemning him over the army's onslaught on Al-Qaeda in the southern province of Abyan.
Yemen's military launched a major offensive in Abyan on May 12 in a bid to drive Qaeda-linked jihadists out of towns and cities in the restive province where they have held sway since May 2011.
Last year AQAP took advantage of the weakness of the central government in Sanaa during protests against ousted president Ali Abdullah Saleh to expand its presence in the impoverished country.
Protesters took to the streets again on Tuesday demanding to bring Saleh and his aides to justice over the killing of protesters during a year of demonstration against his rule that lasted 33 years.
The protest, the largest since February, had been called for last week by the Committee of the Youth of the Peaceful Revolution.
"The number of participants has exceeded 200,000," said a member of organising committee, while another said protesters covered around five kilometres (three miles) along Al-Zubairy main street of the capital, when others were still joining.
Although he stepped down, Saleh is believed to be working behind the scene to undermine the political transition in the country. Some go as far as accusing him of instigating violence.
"If the immunity remains, Saleh and his followers will be encouraged to continue in sabotaging oil (pipelines), and electricity grid, robbing, and supporting terrorism," said a banner carried by demonstrators.
The oil ministry said earlier this month that an explosion hit Yemen's main oil pipeline sabotaging transfers of crude to the country's Red Sea export terminal.