Yemeni air force strikes killed 13 suspected Al Qaeda-linked militants in the south yesterday, local officials said, as the armed forces fought to quell a stubborn Islamist insurgency.

Residents said the aircraft had attacked suspected militant strongholds in Jebel Yasuf and Al Minyasa in the Loder area, where officials say more than 200 Islamist fighters have been killed in less than two weeks.

Militants have exploited a year of upheaval that severely weakened central government control over whole swathes of Yemen to strengthen their foothold in the impoverished state, particularly in the south.

Recently elected President Abd-Rabbu Mansour Hadi is also grappling with a southern secessionist movement and a rebellion by Shia Muslims who have effectively carved out a state within a state in the rugged northern province of Saada, on the border with Saudi Arabia.

An official said eight people were killed near the city of Saada yesterday in a shootout between Shia rebels known as Houthis and Sunni Muslim Salafis who attend a religious school in the area.

Fighting broke out when four Salafi students approached a checkpoint manned by Houthis on the outskirts of the city and shooting broke out, the official said. Four people died on each side and each accused the other of firing the first shot.

The Houthis have fought regularly with Salafis in Saada.

Saudi Arabia briefly fought the Houthis in north Yemen after the Houthis grabbed a piece of Saudi territory in 2009.

The US envoy to Yemen said earlier this year there were signs that Shia Iran was becoming more active in Yemen. Iran denies interfering there, but Saudi Arabia says Iran is fomenting unrest among Shias in eastern Saudi Arabia and in neighbouring Bahrain.

Separately, the defence ministry said an infantry brigade commanded by rebel General Ali Mohsen al-Ahmar had withdrawn from the capital, in line with a plan to demilitarise the streets of Sanaa.