A suicide bomber has killed at least 96 people in the Yemeni capital of Sanaa after infiltrating a military parade dressed as a soldier.

The bomber mingled with soldiers before detonating the device near the presidential palace, eyewitnesses reported.

We were in a parade, suddenly there was a huge explosion. Dozens of our men were killed. We tried to help them, Col. Amin al-Alghabati told Reuters.

The suicide bomber was dressed in a military uniform. He had a belt of explosives underneath, he added.

The attack happened while the defense minister and chief of staff were present, but they were uninjured in the blast.

It is the deadliest bombing in the city since February, when president Abd-Rabbu Mansour Hadi took power.

The parade was scheduled for this Tuesday to mark Yemen's 22nd anniversary of reunification.

The soldiers who were targeted in the attack were troops from Yemen's Central Security, a paramilitary force headed by ousted president Saleh's nephew, Yahya Saleh.

This is a real massacre, said Ahmed Sobhi, one of the soldiers who witnessed the explosion. There are piles of torn body parts, limbs, and heads. This is unbelievable.

Yemen has become a hotbed for al-Qaeda in the Arabian Peninsula for several years now, with the government suffering a series of humiliating defeats and losing vast areas of the country to the insurgents.

The attack coincided with a Yemeni government crackdown against al-Qaeda militants, who control several towns in the south of the country.

Yemen's former president, Ali Abdullah Saleh, resigned in February as part of a U.S.-backed power-transfer deal.