Turkey is to pick a new long-range air defence missile system soon, as tension builds with neighbouring Syria, media and foreign diplomats said Friday.

Companies vying for the four billion dollar (3.2 billion euro) contract include Raytheon and Lockheed Martin of the United States, Rosoboronexport of Russia, CPMIEC of China and the French-Italian consortium, Eurosam, they said.

A Western diplomatic source said a shortlist would be announced on July 11 or 12.

The news comes a week after Syria shot down a Turkish warplane, prompting Turkey to start beefing up its forces along their lengthy border with anti-aircraft guns, missile batteries and tanks.

The Western diplomat said France had a better chance of winning the order following Francois Hollande's May election in succession to Nicolas Sarkozy, who upset Turkey with plans to make denial of the Armenian genocide a criminal offence.

China and Russia are unlikely to secure the contract for Turkey, a NATO member, since they are not part of the alliance, Hurriyet Daily News reported.

Turkey also hosts a NATO early warning radar as part of a new defence system aimed at protecting Europe from missiles coming from the Middle East, notably Iran.