Medical charity Doctors Without Borders (MSF) called on Syria's warring groups and the international community to put as much effort into helping civilians as dealing with chemical weapons.

"Influential countries gathered around a table thrashed out an agreement on chemical weapons and put it into practice.

"They have shown it can be done, so where are the efforts to repeat this success with the burning question of access for humanitarian aid?" asked MSF general director Christopher Stokes.

The MSF appeal came four days after the Organisation for the Prohibition of Chemical Weapons (OPCW) won the Nobel Peace Prize for its work to rid the world such arms.

The OPCW currently has workers in Syria dismantling a large chemical arsenal thanks to a UN security council resolution that staved off threatened US military strikes and was brokered through exhaustive diplomatic wrangling.

MSF called for humanitarian aid to be treated as an equally pressing priority.

It said that many parts of Syria are under siege and sealed off from aid workers, either because access is blocked by President Bashar al-Assad's troops or intense fighting.

It pointed to the Damascus suburbs of East and West Ghouta, which OPCW inspectors have visited but where MSF said medics report "desperate" drug shortages and cases of malnutrition due to lack of food.

"Syrian people are now presented with the absurd situation of chemical weapons inspectors freely driving through areas in desperate need, while the ambulances, food and drug supplies organised by humanitarian organisations are blocked," said Mr Stokes.

Five million Syrians have fled their homes during the two-and-a-half-year-old conflict.

The United Nations says the Syrian government has reduced the number of visas for humanitarian groups and placed strict conditions on distributing aid to opposition-controlled zones.

The kidnapping of seven International Committee of the Red Cross and Red Crescent aid workers in northern Syria at the weekend, four of whom were freed on Monday, has also highlighted the dangerous conditions facing aid groups.