Syrian government air strikes on rebel-held areas of Aleppo continued for a tenth straight day, leaving at least 15 people dead.
The Britain-based Syrian Observatory for Human Rights said Syrian aircraft dropped so called "barrel bombs" on the Sukkari neighborhood of Aleppo Tuesday.
The group says more than 300 people have been killed since the start of the bombing campaign in and around the northern city.
Human rights groups have condemned the use of "barrel bombs" which are made up of metal drums filled with explosives and metal fragments.
The White House on Monday condemned the "indiscriminate" attacks in and around Aleppo. It said the Syrian government must respect its obligation to protect the civilian population and do more to facilitate the safe and unhindered delivery of humanitarian assistance to those in need.
International diplomats are preparing a United Nations-sponsored peace conference in Switzerland next month.
The opposition Syrian National Coalition has threatened to pull out of talks if the bombing in Aleppo continues.