John Kerry, US secretary of state, met Sergei Lavrov, his Russian counterpart, on Sunday evening in Paris for talks that could shape Ukraine’s future as Russian troops mass on the country’s border.

The talks follow a late-night phone call from Russian President Vladimir Putin to US President Barack Obama on Friday, when the two discussed potential diplomatic solutions to the Ukraine crisis. In a sign of the apparent urgency both sides placed on the talks, Mr Kerry turned his aircraft round after a refuelling stop at Ireland’s Shannon airport on Saturday to return to Paris for the meeting.

Russia restated demands it made two weeks ago as it moved to annex Ukraine’s Black Sea peninsula of Crimea. These included: military and political neutrality for Ukraine; the creation of a constitutional assembly; adoption of Russian as a second state language; elections to all state and regional bodies after constitutional reforms; the confiscation of illegal arms and the clearance of areas occupied by protesters in Kiev; and recognition of the result of the Crimean referendum.