Another 17 people were wounded in the violence, medical staff said.

North of Taiz in the capital city of Sanaa, peaceful pro- and anti-government protests were held after prayers on July 15, with many thousands of people attending each event.

They occurred a day after a US drone strike targeting militants in southern Yemen killed at least 50 people, two Yemeni security sources said.

The airstrike occurred in al-Wathee district in Abyan province. One of the sources said more than a dozen people were wounded.

The strike targeted a police station that had been taken over by suspected al Qaeda fighters, the sources said. US drones had been seen flying over the area in recent days, and more attacks were expected, the sources said.

At least seven vehicles and other equipment belonging to the fighters were destroyed.

"The casualty toll is high because fighters were gathered in that area with their family members," said a senior security source in Abyan.

Two witnesses said that at least 30 civilians who had been hiding from the attacks were among the dead.