"A group of Al-Qaeda terrorists in two vehicles opened machinegun fire on a checkpoint, killing seven policemen" in Shibam, a town in the province of Hadramawt, the official told AFP.
Another security official told AFP that suspected Al-Qaeda gunmen riding a motorbike shot and wounded Colonel Abboud Fadhl, an intelligence officer, in the leg late Saturday in the southern province of Lahij.
Al-Qaeda-linked militants from the group Partisans of Sharia (Islamic law) have launched a wave of attacks in the region since former president Ali Abdullah Saleh handed power to his deputy, Abdrabuh Mansur Hadi, in February.
On Saturday, heavy fighting between the army and Islamist fighters who tried to take over several military posts killed 40 people -- 28 soldiers and 12 militants -- in Lahij province, officials said.
Al-Qaeda members also sabotaged a 320-kilometre (200-mile) gas pipeline linking Marib province to Balhaf terminal on the Gulf of Aden, all in the country's restive south, on Friday.
That came shortly after two US drone attacks in eastern Yemen targeted Al-Qaeda suspects, killing seven people, six of them militants, according to an official in Shabwa province.
The Partisans of Sharia have exploited a central government weakened by a year of anti-regime protests to strengthen their position, launching deadly attacks against the army especially in the lawless south and southeast.
Last month, 185 soldiers were killed in a massive assault by Al-Qaeda militants on an army camp near Zinjibar.
The United States says the Yemen-based Al-Qaeda in the Arabian Peninsula, or AQAP, is the most active branch of the global terror network.