US and French defense leaders penned a cooperation agreement on Tuesday designed to help track space debris and avoid collisions of vital satellites.

The accord reflects a new US space security policy that calls for forging an alliance of foreign partners to save costs and counter possible threats to satellites that underpin the American military's high-tech weaponry.

With a growing number of countries operating in space, there was a mounting risk of accidental collisions as well as international disputes, said US Defense Secretary Robert Gates at a joint press conference with his French counterpart, Alain Juppe.

"This arrangement will foster safety and reduce the chances of mishaps, misperceptions and mistrust," Gates said before signing the accord.

The US military and its allies rely heavily on satellites for communications, GPS navigation, spying and targeting, with senior officers increasingly worried about the vulnerability of crucial US satellites.

Gates said cooperation in space was also crucial given the role of satellites in natural disaster warnings, climate monitoring and precision navigation.

The one-page "Statement of Principles" calls for sharing technical data and examining the potential for "combined space surveillance networks" but does not set out detailed plans.

Juppe, whose country leads Europe in terms of space investment, said the agreement marked an "ambitious partnership" and reflected the "high level of confidence" between the two countries.

The space cooperation accord is only the second of its kind, with the United States and Australia signing a similar deal last year.

Negotiations are under way for an agreement with Canada as well, a senior US defense official told AFP.

"We are developing a small number of these agreements with critical allies with whom we want to cooperate closely in space," said the official, who spoke on condition of anonymity.

For years, the United States dominated space and saw little need to seek out international partners.

But with more countries launching or operating satellites and the emergency of anti-satellite weaponry, military leaders want to cooperate more with allies.

"What we're doing is we're shifting from a need to protect information to a need to share this information," the defense official said.

US military radars and sensors track about 22,000 man-made objects in orbit, and experts estimate there are hundreds of thousands of additional pieces of debris that are too small to monitor.

In presenting the new National Security Space Strategy (NSSS) last week, the Pentagon expressed concern over China's pursuit of space weapons that could knock out satellites or jam signals.

In 2007, China shot down one of its own weather satellites using a medium-range ground missile, sparking international concern not only about how China was "weaponizing" space, but also about debris from the satellite.

The United States has reserved the right to respond in "self-defense" to attacks in space.

The two defense chiefs also discussed the crisis in Egypt, the war in Afghanistan, NATO reform and international efforts to "contain" Iran's nuclear ambitions, Gates said.