Four batteries of Patriot missiles arrived in Turkey on Monday as part of a NATO mission to protect the Turkish border from any spillover of the conflict in neighbouring Syria, a NATO source told AFP.

A ship carrying two German Patriot missile batteries anchored at the southwestern port of Iskenderun early Monday and its cargo was being unloaded, the source said on condition of anonymity.

A second ship bearing another two Patriot missile batteries from The Netherlands also arrived at Iskenderun after a two-week journey, waiting behind the German ship to unload its cargo and 300 support troops, the source said.

NATO insists the measure is purely defensive.

"We hope the mission will not take too long," a German colonel was quoted as saying by the private NTV television at the port of Iskenderun. "If we are wanted to stay longer we will do that," he said, speaking in English.

The United States has also begun deployment of two Patriot surface-to-air missile batteries to contribute to the mission, which NATO says will be operational by early February.

Its first shipment arrived by air earlier this month at Incirlik Air Base in Turkey's southeast. Additional equipment will be sent by sea later in January.

The US Patriots "are in Incirlik still," Peter Woodmansee, missile defence chief of the US European Command, told AFP.

"They will move to Gaziantep once the Turkish military finishes preparing the site. I estimate in another five to seven days or so," he said.

The Americans will be based at Gaziantep, 50 kilometres (30 miles) north of the Syrian border.

The six batteries of the US-made missiles, effective against aircraft and short-range missiles, will be deployed in the southern city of Adana and the southeastern cities of Kahramanmaras and Gaziantep, along with 350 troops from each contributing nation.

Turkey requested help from its NATO allies after shells landed on its border areas from Syria in October, killing several villagers.

NATO approved their deployment in December, saying the use of ballistic missiles by the Syrian regime posed a threat to Turkey.

But Syria's allies Iran and Russia oppose the Patriot deployment, fearing that it could spark regional conflict also drawing in NATO.