The United States and France have three aircraft carrier battle groups in the Gulf region, U.S. and French naval sources said on Monday.

The USS Stennis carrier strike group arrived in late February with an additional 6,500 sailors to join the USS Dwight D Eisenhower carrier strike group.

"The Stennis is in the region, in the Arabian sea outside the Gulf and Eisenhower is inside the Gulf," said Lieutenant-Commander Charlie Brown, a spokesman for U.S. Naval Central Command in Bahrain.

"Having a second strike group here is to support ongoing operations in Afghanistan and Iraq and to reassure our regional partners of our commitment to the area," he said.

Strike groups are typically deployed with four to five frigates and destroyers and one submarine, but are then split up between different coalition task forces on arrival, he said.

The French aircraft carrier group Charles de Gaulle arrived in the Arabian Sea in mid-March for operations relating to Afghanistan, a spokesman for the French naval forces in Paris confirmed.

He said the carrier deployed with an air-defence frigate, two anti-submarine frigates, a supply ship and a submarine.

Asked if the carriers, the Stennis and Charles de Gaulle, were within easy reach of the Gulf, the U.S. Navy's Brown replied: "I don't know about easy reach of the Gulf...They are here to fly missions over Afghanistan.

"You can't fly missions over Afghanistan from the Gulf because you'd have to fly over Iran."

Iran's southern coastline stretches into the Gulf of Oman and into the Arabian Sea.

Tensions rose last week between Iran and the West over Tehran's nuclear work and the capture of 15 British servicemen in the northern reaches of the Gulf.

On Sunday Iran said it would limit cooperation with the U.N.'s nuclear watchdog and resolved not to halt its atomic work after the Security Council voted to impose new sanctions.