Russian jets in Syria are carrying air-to-air missiles "for self defence" after the downing of one of their warplanes by Turkey.

Russia's air force said Su-24 jets - of the type shot down by Turkey last week - have flown with an air-to-air weapons system for the first time.

It comes as the US ambassador to NATO confirmed that his country's intelligence supports Turkey's view that Russian jets violated Turkish airspace on November 24.

Defence official Igor Klimov said the air-to-air missiles were capable of hitting targets at a distance of up to 37 miles (60km). 

It comes as the US ambassador to NATO confirmed that his country's intelligence supports Turkey's view that Russian jets violated Turkish airspace on November 24.

Turkey's Prime Minister has ruled out apologising for shooting down an Su-24 on the Syrian border as the diplomatic spat between the two countries intensified.

Ahmet Davutoglu said he had NATO support on his side as he warned that such incidents will continue to be a risk as long as Russia and the US-led coalition worked separately in Syria.

Mr Davutoglu said: "Protection of our airspace, our border is not only a right but a duty for my government and no Turkish premier or president ... will apologise (for) doing our duty."

Russia, meanwhile, announced it is extending its ban on some food stuffs from Turkey to agricultural products, vegetables, and fruits.

Russia's Prime Minister Dmitry Medvedev appeared to raise the pressure on Turkey by saying that Russia could expand the sanctions if needed.

Turkey claims it shot down the Russian Su-24 jet over Turkish airspace because it repeatedly encroached on its territory.

Russia, meanwhile, maintains that the jet never entered Turkish territory and was downed over Syria.

The body of the pilot who died was flown back to Russia from Turkey on Monday after the Turkish authorities took possession of it from an unknown group.

Turkey's President Recep Tayyip Erdogan has asked for a meeting with the Russian President Vladimir Putin on the side lines of the UN Climate Change conference in Paris to discuss the row.

Both Russia and Turkey said there were no plans for Russian President Vladimir Putin and Turkish President Recep Tayyip Erdogan to meet on the sidelines of the UN climate conference.

One of Russia's deputy prime minister said Moscow may delay the introduction of the food import restrictions for several weeks to ease inflationary pressure.