Istanbul (AFP) - Turkey and the United States said Sunday that Washington would withdraw its Patriot missile batteries from the country in October after bolstering Ankara's air defences against threats from Syria's civil war.

The NATO mandate for the mission will run out in October and will not be renewed, but the US is prepared to return Patriot assets and personnel to Turkey within one week if needed, a joint Turkish-US statement said.

"They will be redeployed to the US for critical modernisation upgrades that will ensure the US missile defence force remains capable of countering evolving global threats and protecting Allies and partners, including Turkey," the statement said.

It also emphasised that Washington remains "committed to supporting Turkey's air defence capabilities, including against ballistic missile risks and threats... and its security and regional stability."

A US defence official stressed that the move by the US military was for the purpose of force modernisation.

"It does not reflect a decision by the NATO Alliance to reduce support for Turkey's air defence," the official told AFP.

The decision comes less than a month after Turkey opened its southeastern Incirlik air base to US fighter jets to carry out bombing raids against Islamic State (IS) targets in Syria.

The US and Turkish officials have said their respective armies are currently working to coordinate logistics before starting full-scale operations against IS.

Turkey turned to its NATO allies for help over its troubled frontier after shells landed on its border areas from Syria in October 2012, killing several villagers.

The United States, the Netherlands and Germany have provided a total of six Patriots batteries along the Turkish border with Syria. Germany on Saturday announced it would withdraw its two missile systems from Turkey from January 31, saying that the main threat in the region now came from the Islamic State group.

Originally used as an anti-aircraft missile, Patriots today are used to defend airspace by detecting and destroying incoming missiles. NATO deployed Patriot missiles in Turkey during the 1991 Gulf war and in 2003 during the Iraqi conflict.

Turkey is currently pressing a two-pronged "anti-terror" offensive against IS jihadists in Syria and Kurdistan Workers' Party (PKK) militants in northern Iraq and southeast Turkey following a wave of attacks inside the country.

Ankara launched its first air strikes against IS targets in late July but then put them on hold, instead concentrating its firepower on Kurdish militants in operations that have troubled its allies.