US and Jordanian F-16 fighter jets hit dummy targets in the kingdom's southern desert on Wednesday, while Navy SEALs and other special forces rescued "hostages" and nabbed "terrorists" in mock exercises under major multinational manoeuvrers.

Using live ammunition, six F-16s, two AV-8B Harrier jets, 28 tanks, 20 armoured personnel carriers, 800 US and Jordanian troops took part in a 45-minute drill in Quweira close to the Red Sea port of Aqaba as part of "Eager Lion 2013," which wraps up on Thursday.

Fighters, attack helicopters and tanks attacked ground targets as Jordan's army chief, General Mashal Mohammad Zaben, and King Abdullah II's brother, Prince Faisal watched.

"The goal of the drill is to boost and enhance the capabilities and performance of the Jordanian Armed Forces, including ways to deal with situations in which refugees are involved," Colonel Mekhled Suheim, Eager Lion spokesman, told journalists watching the exercise.

Jordan says it is home to more than 500,000 refugees from next-door Syria and its brutal civil war.

Worried about a possible spillover of violence from Syria to Jordan, a key US ally, Washington has sent a Patriot missile battery and F-16s to the kingdom for the 12-day manoeuvres, and decided to keep them there to counter the threat posed by the Syrian conflict.

But US and Jordanian officials have declined to say how many F-16s would be taking part in the joint exercise, aside from the six seen on Wednesday, or how many might stay on afterwards.

US media reports have said Washington was preparing to use the weapons to enforce a no-fly zone over Syria from Jordan, but the White House has ruled out the idea, billing it as difficult, dangerous, costly and unsuitable.

"Eager Lion 2013 is a great opportunity to share expertise and boost capabilities (of troops)," Brigadier General Gregg P. Olson of the Marine Corps Forces Central Command said as he mingled with journalists.

Following the drill in Quweira, the army drove journalists about 50 kilometres (31 miles) to Aqaba's anti-terrorist unit.

Some 50 US Navy SEALs as well as Jordanian and Iraqi special operations troops took part in a 30-minute mock exercise to rescue hostages on a ship "hijacked" by pirates off the coast of Aqaba.

Eight Jordanian gunboats and three attack helicopters intercepted the ship. Masked frogmen boarded it and took control before rescuing the hostages.

"This is a difficult exercise because the target is moving," said a US officer as he observed the operation.

Frogmen later raided a building on the beach in another mock drill to arrest the mock terrorists, using coloured smoke bombs and tear gas.

Suheim said the destroy USS Stockdale will leave Jordanian waters after Eager Lion concludes.

Around 4,500 US troops, 3,000 Jordanian soldiers and 500 observers from 19 countries, including Britain, France, Italy, Qatar, Turkey and Saudi Arabia, are participating in the exercise, staging battlefield, logistics and humanitarian exercises.

"The US troops will start departing Jordan on June 25," Major General Robert G Catalanotti of the US Army Central Command told AFP.

A US defence official has said that, after consultations with Jordan, the Americans would also keep a unit of Marines on amphibious ships off the country's Red Sea coast.

The Pentagon had already sent about 200 troops to Jordan to help it prepare for possible military action in Syria, including scenarios to secure the regime's chemical weapons stockpiles.

Jordan is a major beneficiary of US military and economic aid, with Washington granting $2.4 billion (1.85 billion euros) over the past five years, according to official figures.