Yemeni officials say a suicide bomber rammed his explosives-laden car into an army checkpoint in the country's volatile south Saturday, killing three soldiers and wounding seven others.

The officials said the bomber drove up to the checkpoint on the road between the port city of Aden and Zinjibar and blew himself up.

Militants have a strong presence in the region, which has seen frequent battles between Yemeni security forces and al-Qaida insurgents. The unrest has increased amid the political turmoil following mass protests against longtime President Ali Abdullah Saleh. Mr. Saleh is recovering in neighboring Saudi Arabia from wounds sustained in an assassination attempt in June.

Earlier Saturday, military sources and medical officials said another three soldiers and 12 militants were killed in clashes between Islamists and military units advancing on Zinjibar.

President Saleh has said he is committed to holding presidential elections. However, Yemen's opposition has turned down such offers, demanding Mr. Saleh's ouster.