Fifty-seven countries, led by Switzerland, are calling for the United Nations Security Council to refer the Syria conflict to the International Criminal Court for an investigation into war crimes.
The letter, sent on Monday to the 15-member Security Council, cites the findings of a U.N. panel documenting torture, sexual violence and summary executions that have occurred in Syria since the start of the uprising in March 2011.
It demands the Security Council open an ICC investigation "without exceptions and irrespective of the alleged perpetrators."
As the violence continues, humanitarian groups are calling on the international community to increase aid for refugees driven from their homes by the crisis.
The International Rescue Committee
issued a new report Monday warning that the region faces a "staggering humanitarian disaster." It outlines the challenges refugees face in accessing health care, as well as what it calls "horrific levels" of sexual violence that many families cited as their reason for fleeing Syria.
The group is urging donors to meet calls by the United Nations for $1.5 billion in funding, as well as other resources to help neighboring countries now housing thousands of Syrian refugees.
Selena Victor, advocacy director with the IRC, said even if the conflict in Syria ends, the effects of the fighting will leave a long-term, large-scale need for refugee and reconstruction aid.
"The needs are enormous - there are two million people who have been forced to flee their home, half a million refugees in the region," said Victor. "The whole of the infrastructure inside Syria has been basically decimated. And the impact on people has been absolutely massive. The reconstruction efforts required will be enormous, and I think we need to take that on board right now."
The violence continued Monday with Syrian fighters jets continuing to bomb the Damascus suburbs. Activists say air strikes on the rebel-held town of Moadamiyeh, southwest of the capital, killed at least 13 people, including women and children.
Syrian security personnel, members of the civil defence and civilians gather at the site where a large blast hit a neighborhood of Aleppo, January 18, 2013.
A Free Syrian Army fighter runs for cover at a suburb of Damascus, January 17, 2013.
Residents stand near buildings damaged by missiles fired by a Syrian Air Force fighter jet in Daraya, January 17, 2013.
A Free Syrian Army fighter holds a rifle in the Ain Tarma neighborhood of Damascus, January 15, 2013.
Syrians gather at the scene of an explosion outside Aleppo University, between the university dormitories and the architecture facility, January 15, 2013.
A street vendor sells cotton candy in Aleppo, January 15, 2013.
A woman walks near a crater caused by missiles fired by a Syrian Air Force fighter jet near Idlib, January 15, 2013.
Buildings in Erbeen, near Damascus, damaged by missiles fired by a Syrian Air Force fighter jet, January 15, 2013.
Internally displaced Syrian children sit on a bench at a school in Aleppo, January 14, 2013.
People gather at a site hit by missiles fired by a Syrian Air Force fighter jet in Azaz, north of Aleppo, January 13, 2013.
A Free Syrian Army fighter aims his weapon in the Saif al-Dawlah neighborhood of Aleppo, Syria, January 13, 2013.
A farmer transports a tree which will be used for heating in the countryside of Idlib January 13, 2013.
A boy, standing next to his father, cries as they wait to receive humanitarian aid in the countryside of Idlib January 13, 2013.
The Syrian government has been waging an offensive to dislodge rebels from strategic areas around Damascus. Activists reported at least 130 deaths across the country Sunday.
Meanwhile, Russia urged the rebels to make counter-proposals to those made by Syrian President Bashar al-Assad in a recent speech to start a dialogue that could end the fighting.
Russian Foreign Minister Sergei Lavrov said Sunday that if he were "in the opposition's place," he would come up with ideas in response on how to establish a dialogue.
He repeated Russia's position that the opposition's demand for Assad to quit could not be a precondition for peace talks to end the 21-month conflict that has killed at least 60,000 people.