Yemeni security forces have killed four al-Qaeda militants suspected of killing 10 people, including eight Spaniards, in a suicide attack, officials say.

The militants died during a raid near the city of Mareb east of the capital, Sanaa, on Wednesday morning.

One of the dead was Kassem al-Raimi, an alleged top al-Qaeda operative thought to have masterminded the bombing.

The eight tourists, along with two Yemenis, died in the 2 July attack at Mareb's Queen of Sheba temple.

Up to 12 people were injured in the attack, in which a suicide bomber drove an explosives-laden car into their convoy.

Yemen has faced continuing unrest in recent years, which the government often blames on al-Qaeda operatives.

'Long-term threat'

Security sources said Raimi, a Yemeni national, was involved in several other operations, and was one of 13 convicted prisoners who escaped from a Sanaa prison in 2006.

At least two of the other three militants killed were Yemeni, they said.

On Monday, the US embassy warned Americans living in Yemen saying that the terrorist threat in the country had "evolved".

"We are now experiencing terrorist actions previously unseen in Yemen," the embassy's note said.

"Western interests may continue to be targeted. This evolving threat is not temporary, and will be with us for the foreseeable future."

In recent years Yemen's government has been fighting Islamists with the help of US special forces based in Djibouti, on the Horn of Africa.

Al-Qaeda has demanded the release of militants jailed in the country.

PHOTO CAPTION
People gather around the aftermath of the explosion in Yemen