Amateur video purports to show the suffering of starving children in Syria as an ongoing siege of two towns prevents basic supplies from getting through. According to the Syrian Observatory for Human Rights (SOHR), residents of the town of Madaya in Damascus province are starving to death, as government forces, backed by Hezbollah fighters, maintain a blockade.

Syrian state media has said two towns near Idlib, Kefraya and Fua, have been besieged by anti-government fighters for two years. One protester accused the Syrian government of violating the terms of the agreement.

He said: "This protest is a reaction to the suffering of our people in Zabadani and Madaya and all the towns that have been part of deals with the regime. The regime has led these towns into truces but has breached these deals even with the presence of organisations like the UN.

"This is why all of our people from all different groups and with all their capacities have to hand the situation over to the military leaderships to achieve a real advancement that will make others feel that we can do to them what they can do to us.

"Currently the tragedy is in Madaya and Zabadani and from here we can appeal to our brothers in Idlib to do what they can do to pressure Kefraya and Fua so that the action can be an example."

The SOHR says there are 40,000 people in Madaya, including 20,000 who fled from Zabadani. Hundreds of children are suffering from severe malnutrition, the organisation says. The UN's Syria mediator aims to convene peace talks in Geneva on 25 January in the latest effort to end nearly five years of civil war in which more than 250,000 people have died.