Washington (AFP) - The US military backed up Turkey's claim Tuesday that Turkish pilots warned a Russian jet 10 times -- but failed to get a response -- before shooting it down after it briefly entered Turkish airspace.

"We were able to hear everything that was going on, these (communications) were on open channels," Baghdad-based military spokesman Colonel Steve Warren said in a video call with reporters.

He added it was not immediately clear on which side of the Turkish-Syrian border the Russian jet had been flying, and it would take some time to analyze data before arriving at that determination.

Turkish Ambassador to the United Nations Halit Cevik said in a letter to the Security Council that two Russian planes had flown a little more than a mile into Turkish airspace for 17 seconds.

A US defense official, speaking on condition of anonymity, confirmed the timing but said it remained unknown if Turkey had fired on one of the jets as it was in Turkish airspace, or after it had crossed back into Syria.

The Pentagon says no US forces were involved in the Turkish downing of the Russian jet.

The United States has a strong presence in Turkey and regularly flies warplanes out of the air base in Incirlik as it conducts bombing runs against Islamic State targets in Syria and Iraq.

Pentagon officials have previously condemned the actions and tactics of Russian pilots after Russian jets twice violated Turkish airspace last month.

In Tuesday's incident, the Turkish army said the plane was shot down by two Turkish F-16s after violating Turkish airspace 10 times within a five-minute period.

Russia insists the jet was inside Syrian airspace and condemned the downing as "a very serious incident."

UN Secretary-General Ban Ki-moon on Tuesday called for urgent measures to de-escalate tensions.