Nagorno-Karabakh: at least three Syrian fighters killed

Syrians on the ground are believed to be contractors working for Turkish security companies

At least three Syrian opposition fighters have been killed in skirmishes in the disputed region of Nagorno-Karabakh, the Guardian has learned, confirming earlier reports of foreign involvement in the battle between Armenian and Azerbaijan over the territory and increasing fears it may spiral into a wider regional conflict.

As fierce combat between Armenian and Azerbaijani forces stretched into a fourth day, the presence of Syrians on the ground - believed to be contractors working for Turkish security companies - signalled a new frontier for Ankara's increasingly assertive foreign policy.