US planes operating from an aircraft carrier in the eastern Mediterranean have mounted at least 35 air strikes on Islamic State jihadists since relocating last week from the Gulf, officers on board told AFP Tuesday.

In an operation commanders said was aimed at demonstrating the strength and flexibility of US forces in the region, F-18 fighter jets and support aircraft deployed on the USS Harry S. Truman made 50 combat sorties between Friday and midnight on Monday (2300 GMT).

In 35 of them, ordnance was dropped with the strikes split evenly across Syria and Iraq, the carrier's spokesman, Lieutenant Tim Pietrack, told reporters on board the ship.

All of the strikes were carried out while providing air support to fighters on the ground rather than the kind of direct attack that blew up a bank used by IS in the Iraqi city of Mosul in January.

They also scattered pamphlets aimed at bolstering morale among forces fighting IS or warning civilians of imminent attacks in their area.

Since the Truman passed through the Suez Canal on Thursday, all of the destructive ordnance used has been 500-pound laser- or GPS-guided missiles, said the Truman's Weapons Officer Jim McDonald.

"The difference is that with a 500-pound smart bomb, you can put it in a living room if you want to, rather than take out a whole house," added McDonald, known onboard as "Gun Boss".

In contrast, the operation that took out the Mosul bank and sent millions of dollar up in smoke involved multiple drops of 2,000-pound munitions, he said.

"Since we started combat operations in the Gulf on December 29, we have been only been doing maybe one direct strike a week," he said.

"Most of it has been about close air support and targets of opportunity. We have not used a single 'dumb' weapon on this deployment."

- Mission extended -

The latest attacks take to more than 1,450 the total number of bombs dropped by planes operating off the Truman since it left Norfolk, Virginia for the Gulf in mid-November.

The giant, nuclear-powered carrier, its 70-plus aircraft and its 5,500-strong crew had been due home in the middle of this month.

But President Barack Obama extended its mission by an additional 30 days as part of efforts to intensify the campaign to hit IS directly, destroy its revenue streams and embolden its enemies.

The extension has been billed as a reflection of the success Carrier Strike Group Eight (CSG 8 - the battle group centred on the carrier) has had in helping weaken IS to the point that it has now been pushed out of almost half the territory it once occupied in Iraq.

But the reasons for moving the Truman to waters off Syria's western coast are unclear.

Analysts suggest Washington may be sending a signal to Turkey that it does not need to use airbases there to influence events in Iraq and Syria. Or the show of strength could be intended for the eyes of Russia, whose warplanes are also engaged in Syria, in support of the Damascus regime.

- More action in Syria -

Operating out of the Mediterranean could provide valuable experience if the US is drawn into more active involvement in combatting IS-linked forces gaining a foothold in Libya.

"That could happen but that is not why we are here right now," said CSG 8's commander, Rear Admiral Bret Batchelder.

"The significance (of switching to the Mediterranean) is the illustration that we can operate anywhere in the world that we want to, to enforce strategic objectives."

Asked how he assessed the state of the campaign as his involvement nears an end, the Iraq and Afghanistan veteran said: "Yes, I feel like we are getting the job done, which is not just us, it is all of the 65 countries participating in the coalition."

As well as making life more comfortable aboard, out of the searing heat of the Gulf, the admiral says the move to the Mediterranean has led to his pilots undertaking more missions to Syria than previously.

"That is just based on proximity and the management of forces ... but we are also supporting the same areas that we did from the Arabian Gulf."