WASHINGTON (Reuters) - The U.S. Navy has sent an aircraft carrier and a guided-missile cruiser into the waters near Yemen to conduct maritime security operations, a Pentagon spokesman said on Monday, but he denied the ships were on a mission to intercept Iranian arms shipments.

The U.S. Navy sent the carrier USS Theodore Roosevelt and its escort cruiser, USS Normandy, from the Gulf into the Arabian Sea on Sunday. Army Colonel Steve Warren, a Pentagon spokesman, denied reports the ships were on a mission to intercept Iranian arms shipments to Yemen.

The ships will join seven other U.S. warships in the waters near Yemen, which is torn by civil strife as Iranian-backed Houthi rebels battle forces loyal to the U.S.-backed president.

The Shiite Muslim Houthi fighters sidelined the central government after seizing the capital Sana'a in September and expanding across Yemen, which borders oil giant Saudi Arabia.

Saudi Arabia and a coalition of its Arab allies have launched air strikes in an effort to stop the advance of the Houthis, a move Tehran has condemned.

One U.S. official said the presence of the U.S. warships off Yemen give American decision-makers options for action in the event the situation deteriorates.

The other U.S. warships in the region include two destroyers, two mine-sweepers and three amphibious ships carrying 2,200 U.S. Marines.