"Agreeing a negotiated peace is going to be difficult, however committing to ensuring humanitarian aid reaches all those in need shouldn't be," the NGOs said in a joint appeal issued at the Davos World Economic Forum as peace talks opened in another Swiss town, Montreux.
"We call on the international community to stand up for the people of Syria who are enduring the worst humanitarian crisis of our time."
The groups, which included Amnesty International, Care USA and Oxfam International, said half of Syria's population was dependent on humanitarian aid after nearly three years of civil war. Disease and starvation were rife in certain areas and the current situation "defies the basic norms of a civilised world."
Oxfam Executive Director Winnie Byanyima said there had to be more pressure put on regional powers -- an apparent reference to Saudi Arabia, the main backer of the opposition, and Iran, which has propped up Bashar al-Assad's regime.
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"Peace is very much in the hands of regional leaders," she said.
Amnesty's Secretary General Salil Shetty accused European governments of hypocrisy in failing to match their expressions of concern about Syria with respect for their obligations to accepting refugees from the crisis.
"Seeking asylum is a legal right and several European countries are not following that principle," Shetty said.
The other organisations associated with the appeal were Human Rights Watch, Mercy Corps, Save the Children International and World Vision.