Boris Johnson has called for the Syrian regime and its Russian backers to allow emergency food and medical supplies through to desperate civilians besieged in Aleppo after international talks in Paris.

The Foreign Secretary said top priority was securing aid access to ease the "dire" situation in the east of the city, which Bashar Assad's forces have all but recaptured from opposition rebels.

Russia said 50,000 Syrians have fled the area over the past two days amid a Syrian ceasefire but the activist-run Syrian Observatory for Human Rights reported heavy clashes were still ongoing.

READ MORE: Gove concedes that his name is now synonymous with treachery

Mr Johnson flew to Paris for emergency talks with US secretary of state John Kerry, along with other European and Arab counterparts.

He said: "The situation in Aleppo remains dire with desperate images of destruction and a flagrant disregard for human life being splashed across the media on a daily basis.

"We agreed our first priority must be the protection of civilians and ensuring access for humanitarian aid. It's essential that the regime and its backers provide the United Nations that access with immediate effect.

"Although the deterioration of the situation in Aleppo will be a setback for the Syrian opposition it will not change the fundamentals of the conflict. There can be no military solution in Syria.

READ MORE: Gove concedes that his name is now synonymous with treachery

"We must keep pushing for a return to a political process with the credibility necessary for all parties to commit to an end to all the fighting."