Yemeni officials say a suicide bomber has attacked a military parade rehearsal in the capital Sana'a, killing at least 63 troops and wounding more than 60 others.

Officials say the bomber was dressed in a military uniform and detonated the explosives as hundreds of soldiers gathered around him. Yemen's defense minister was at the rehearsal but was unharmed.

The soldiers were preparing for a parade on Tuesday to mark the unification of Yemen's north and south. Yemeni President Abed Rabbo Mansour Hadi was due to attend the parade.

No group has claimed responsibility for the attack. It coincides with a U.S.-backed Yemeni government offensive against al-Qaida militants who seized parts of the country's south last year as it was engulfed in a popular uprising against then-president Ali Abdullah Saleh.

Mr. Hadi, who succeeded Mr. Saleh in February, has vowed to fight the growing presence of the terrorist network's regional affiliate, al-Qaida in the Arabian Peninsula.