Among the dead at the Defense Ministry complex, which also houses a military hospital, were soldiers and civilians, including seven foreigners — two Germans, two Vietnamese, two Filipinos and one Indian, according to the Supreme Security Commission.

Aden, Yemen: The Defense Ministry came under attack Thursday from a suicide car bomber and heavily armed gunmen, killing 52 people and wounding 167 in a fierce battle in the heart of Yemen's capital of Sanaa, the government said.

Among the dead at the Defense Ministry complex, which also houses a military hospital, were soldiers and civilians, including seven foreigners — two Germans, two Vietnamese, two Filipinos and one Indian, according to the Supreme Security Commission.

Nobody immediately claimed responsibility for the two-stage assault, but suicide bombings and complex attacks are the hallmarks of al-Qaeda.

The brazen morning attack, the deadliest in Sanaa since May 2012, underlined the ability of insurgents to strike at the government as they exploit the instability that has plagued this key US ally for more than two years. Defense Minister Mohammed Nasser Ahmed was in Washington for talks Thursday, and the US State Department condemned the "senseless killing and wounding of dozens."

The US considers Yemen's al-Qaeda branch, known as al-Qaeda in the Arabian Peninsula, to be the most active in the world. In recent months, Washington has sharply escalated drone attacks against the militants in the impoverished nation. US forces also have been training and arming Yemeni special forces, and exchanging intelligence with the central government.

The terrorist network gained a major foothold in the south, taking over several towns in the chaos that followed the 2011 uprising that ousted longtime President Ali Abdullah Saleh. The drone strikes and a series of US-backed military offensives helped uproot several key militant strongholds, but al-Qaeda continues to fight back.

In an attack blamed on al-Qaeda in May 2012, a suicide bomber blew himself up amid troops taking part in a parade rehearsal near the presidential palace in Sanaa, killing 93 soldiers.

The government statement said all the militants who stormed the complex Thursday were killed, but it did not say how many. State TV showed a dozen bodies, identifying them as the attackers.

Military helicopters hovered over the site as soldiers and ambulances arrived and gunfire echoed in the streets.

President Abed Rabbo Mansour Hadi, who succeeded Saleh, later met with military commanders inside the devastated complex and ordered an investigation into the incident, military officials said.

In Berlin, Foreign Minister Guido Westerwelle confirmed that two Germans and a Yemeni who worked for the aid organisation GIZ were killed.

Military officials said the attack may have been timed to target a planned meeting of top commanders, although the session was unexpectedly delayed. They added that two army vehicles disappeared from the complex last month, but they did not know whether those were used in the assault.

The Defense Ministry was tipped off last week that a major attack in the capital was imminent, prompting authorities to reinforce security forces, the officials said.

The officials spoke on condition of anonymity because they were not authorized to talk to the media.

Marie Harf, a deputy spokeswoman for the US State Department, condemned the attack.

"We stand with Yemen against this violence and remain firmly committed to supporting the Yemeni people as they seek to conclude the National Dialogue and move forward peacefully with Yemen's historic democratic transition," she said.

Westerwelle also denounced what he called "this cowardly attack."

"These terrible crimes cannot be justified," he said, urging the authorities to find those responsible for the attack.

"Yemen must not become a place of terrorism," he said.

UN Secretary-General Ban Ki-moon added his condemnation and believes "the only path to a stable, prosperous and democratic Yemen is through the ongoing peaceful and all-inclusive National Dialogue Conference," UN spokesman Martin Nesirky said.

Yemen is strategically located at the southwest corner of the Arabian Peninsula, bordering Oman and Saudi Arabia, two of Washington's closest Arab allies. Yemen has a shoreline on the Red Sea and the Arabian Sea close to the vital shipping lines carrying oil from the energy-rich Gulf region to the West.

AP