Related: Second U.S. Aircraft Carrier Arrives in Persian Gulf

The US Navy said on Tuesday it is staging major war games in the Gulf with two aircraft carriers for the first time since the 2003 invasion of Iraq, at a time of heightened tension with Iran.

The manoeuvres involve the USS John C. Stennis, the USS Dwight D. Eisenhower and their battle groups.

They are being held as tensions run high between the West and the Islamic republic over Tehran's nuclear drive and the capture last week of 15 British marines and sailors in a waterway between Iran and Iraq in the northern Gulf.

"Two air wings from the aircraft carriers will conduct air warfare exercises while the surface components will conduct exercises in three general disciplines: anti-submarine, anti-surface and mine warfare," the Fifth Fleet said in a statement.

"This exercise demonstrates the importance of both strike groups ability to plan and conduct dual task force operations as part of the US long-standing commitment to maintaining maritime security and stability in this region."

The Fifth Fleet is based in Bahrain, an island state which lies across the Gulf from Iran.

The United States announced in January that it plans to keep the two carrier battle groups in the Gulf for months to step up the US military presence in the oil-rich region.

US President George W. Bush said the moves were aimed at bolstering security and protecting US interests in the Middle East, while Defence Secretary Robert Gates said the deployment was a signal to Iran.

"It will be the first time since '03 that we've had two carriers in the region," said a senior US military official, referring to the year of the US-led invasion of Iraq.

The USS John C. Stennis group with its 6,500-strong force, which has been in the Gulf of Oman since February 19, entered Gulf waters on Tuesday escorted by the guided-missile carrier USS Antietam, the Fifth Fleet said.