"We are surprised at groundless allegations in several media reports lately on the presence of British soldiers and on the arrival of US forces to aid in fighting terror in Yemen," the Defense Ministry's 26sep.net news website quoted a Yemeni official as saying.

The official said that Yemen's cooperation with the "United States or other countries" in fighting terrorism is "restricted to the exchange of information which facilitates its hunt (for) terrorist elements and handing them over to justice."

Suspected Al-Qaeda militants have carried out several attacks in past weeks against Yemeni soldiers, the latest of which killed nine soldiers and a civilian in the town of Jaar in the southern Abyan province on Saturday, according to a security official.

The soldiers were breaking the Ramadan fast at sunset when four armed militants attacked them using rocket-propelled grenades.

The militants shouted they had come "from the town of Loder to avenge the death of our brothers there," the security official said, quoting a soldier who had escaped the attack.

"The attack carries the fingerprints of Al-Qaeda," he added.

Deadly clashes last week between alleged Al-Qaeda militants and the army in Loder, in northern Abyan, killed at least 33 people, including 19 militants.

The Interior Ministry on Saturday called for tighter security at intelligence headquarters throughout the country and said it had put security units on alert.

The ministry, in a statement posted on its website, stressed "the importance of increasing security vigilance and deploying patrols in the capital and the provinces, in addition to tightening security measures on vital facilities and buildings."

An unnamed US counter-terrorism official had told AFP on Wednesday that the United States was increasingly concerned about the threat posed by Al-Qaeda in Yemen and that it was moving to pile pressure on the militants.

He said Al-Qaeda affiliates had regrouped in Yemen and emerged as a "virulent" danger.

Yemen's president said intensifying Al-Qaeda attacks are his government's biggest challenge, though his military leaders refused Sunday to accept the intervention of foreign troops.

President Ali Abdullah Saleh compared the recent attacks to the violence against government forces in Iraq and Afghanistan. In an address at a mosque on Saturday, he appealed for clerics and Yemen's people to back him in the fight.

"Our people... should foil this plot," he said. "The citizens should stand by the side of the state. These terrorists... are harming the nation's and the citizens' interests."