NATO experts on Wednesday began a survey of sites that would serve as suitable locations for the deployment of Patriot missiles along Turkey's border with its war-torn neighbour Syria, the state-run Anatolia news agency reported.

Turkey last week asked NATO partners to deploy the surface-to-air missiles after a series of cross-border shellings, including an attack that left five civilians dead.

NATO has yet to formally respond to the request.

The NATO experts were due to visit a military base in eastern Turkey's Malatya province, which already hosts an early warning radar as part of NATO's missile defence system, Anatolia said.

Turkish officials say the number of Patriot batteries and their location would be decided after the visiting team reports back to the alliance.

Aside from Malatya, the Patriots could be deployed in the southeastern provinces of Diyarbakir or Sanliurfa.

Turkey might receive up to six Patriot batteries and some 300 foreign troops to operate the missiles, which are expected to be supplied by The Netherlands or Germany, the two European providers of the US-made weapons.

Ankara insists that any Patriot deployment would be for defensive purposes only.

But the Syrian regime's allies Russia and Iran are deeply opposed to the move, fearing such a deployment could spark broader conflict.