Eight NATO protesters were arrested Monday ahead of a weekend summit when they refused to leave the Chicago office tower which houses President Barack Obama's campaign headquarters, police said.

"They're starting early," Officer Robert Perez of the Chicago police department told Agence France Presse.

A Leica camera prototype made in 1923 fetched 2.16 million euros ($2.79 million) at auction on Saturday, setting a new world record for a camera.

The camera, an exemplar of the pre-production Leica 0-Series, had been expected to go for between 600,000 and 800,000 euros and bidding started at 300,000 euros at the Galerie Westlicht in Vienna.

A U.S. drone killed five suspected members of al-Qaida in two rocket attacks on vehicles transporting the jihadists near Marib in eastern Yemen, a tribal chief said.

"A drone fired two rockets at two vehicles, killing five al-Qaida members," near the village of al-Hosoon, outside the city of Marib, 170 kilometers east of the capital Sanaa, he said.

Two NATO troops were killed by two men in Afghan police uniforms in southern Afghanistan Saturday, the military said, with Afghan sources identifying the victims as British soldiers based in Helmand province.

A spokesman for NATO's International Security Assistance Force (ISAF) said the attackers were believed to be insurgents dressed as police, but a senior Afghan security official said they had been in the police force for a year.

The top commander of NATO-led forces in Afghanistan held talks with Pakistan's army chief in Islamabad Saturday on how to improve security in volatile areas bordering the two countries.

U.S. General John Allen met General Ashfaq Kayani in the Pakistani capital ahead of a high-level meeting of NATO's International Security Assistance Force (ISAF), officials said.

U.S. President Barack Obama called on members of Congress Saturday to pass several initiatives designed to stimulate the U.S. economy and create much-needed jobs.

"There are things we can do - right now - to help create jobs and restore some of the financial security that so many families have lost," Obama said in his weekly radio and Internet address.

The United States said Friday it was partially resuming sales of military supplies to Gulf Arab ally Bahrain after having frozen most shipments last year amid a bloody crackdown on protests.

But in a nod to concerns over ongoing pro-democracy demonstrations, State Department spokeswoman Victoria Nuland said "the items that we are releasing are not used for crowd control."

The double agent who infiltrated al-Qaida and helped foil a plot to blow up a U.S.-bound airliner held a British passport in addition to being a Saudi national, CNN reported Thursday.

The man was sent by Saudi counterterrorism agents into Yemen as a mole after it was learned that al-Qaida in the Arabian Peninsula was developing an updated model of the underwear bomb that failed to explode in a Christmas Day 2009 attempt.

The United States is urging Lebanese banks to take "extra" caution in handling financial transactions with Syria, to prevent the Assad regime and its supporters from stashing money abroad, a senior Treasury official said Thursday.

"We want to be as careful as possible that the regime, its cronies, its allies that may be trying to shield their assets might not be able to do so," said David Cohen, the Treasury's under secretary for terrorism and financial intelligence.

The United States said Tuesday it is "disturbed" by a Russian security crackdown on peaceful protesters and urged the authorities to allow freedom of speech and assembly.

"We're troubled by reports of violence in Moscow during the protests on May 6 and by the arrests that have been carried out over the last three days," State Department deputy spokesman Mark Toner also told reporters.