U.S. Secretary of State John Kerry has criticized the Syrian government for dropping barrel bombs on the northern city of Aleppo.
Activists said those attacks have killed dozens of people in the past week in the city that has seen some of the worst fighting between Syrian forces and rebels opposed to President Bashar al-Assad.
In a statement Tuesday, Kerry said the bombings are the Assad administration's "latest barbaric act," and that the government is focused on inflicting more destruction on the country.
He said the opposition and the international community are trying to find an end to the fighting, while the government's actions "undermined hope" for successful peace talks in Geneva.
The first round of negotiations ended last week with little progress, but United Nations Secretary-General Ban Ki-moon and mediator Lakhdar Brahimi expect delegates from the government and opposition to resume meeting February 10.
Meanwhile, Ban is highlighting what he has called the "alarming impact" of the Syrian conflict on the country's children.
In a report Tuesday to the Security Council, Ban said government forces have killed countless kids, arrested and tortured children and kept them from accessing schools and healthcare.
The report also said opposition fighters have used child soldiers in operations that resulted in casualties, including children, and engaged in summary executions of children as well.
Ban also called attention to the distress caused to Syrian children by witnessing the killing and wounding of their family members.
He said both sides of the conflict must immediately stop abuses against children and protect their rights.
The violations cover a range of parties involved in the nearly three years of fighting in Syria, from government troops and their associated Shabiha militias, to Free Syrian Army rebels and al-Qaida-linked Jabhat al-Nusra fighters.
Syria's conflict began in March 2011 as peaceful protests against the government before spiraling into a civil war that the U.N. estimates has killed well over 100,000 people and forced nearly 9 million from their homes.