Syrian government forces have reportedly killed at least 20 people, including women and children, when they shelled a bakery in a neighbourhood under rebel control in the contested northern city of Aleppo, opposition activists said.
Video footage uploaded to the internet, which could not be immediately verified, appeared to show decapitated bodies amid scattered bread loaves on Tuesday.
Majd Nour, an opposition campaigner in Aleppo, said two shells hit the bakery, located in the eastern Hananu
neighbourhood, in the early afternoon.
Free Syrian Army fighters were guarding it at the time, he said.
Also on Tuesday, Syrian warplanes have raided a district in the northern city of Aleppo as fighting across Syria rages, three days ahead of the Muslim feast of Eid al-Adha during which peace envoy Lakhdar Brahimi has proposed a ceasefire.
The London-based Syrian Observatory for Human Rights, a network of activists, said a rebel was killed in Aleppo, Syria's second city, in fighting which was taking place in several districts.
In the Damascus suburb of Harasta, at least two rebels were killed, the group said.
In the capital itself, security forces carried out searches in the Zahira quarter, where gunfire could be heard. Overnight, one man was killed in a bomb attack on the southeastern outskirts of Damascus.
The Observatory also reported fighting in the eastern province of Deir Ezzor and in Deraa, southern Syria.
Truce in doubt
Despite the violence, the United Nations held to the hope that the foes will observe a truce during the four-day Eid, saying it had plans to assemble a peacekeeping force if a ceasefire takes hold.
"We are getting ourselves ready to act if it is necessary and a mandate is approved," UN peacekeeping chief Herve Ladsous said in New York, cautioning that the plans would need the approval of the 15-nation Security Council.
In-depth coverage of escalating violence across Syria
UN-Arab League envoy Brahimi has said he contacted political opposition leaders inside and outside Syria and armed groups in the country and "found them to be very favourable" to the idea of a truce.
However, the leader of the main Syrian opposition group said chances were slim that a ceasefire can take hold, partly because the plan is too vague.
Abdelbaset Sieda, head of the opposition Syrian National Council, told the Associated Press news agency on Tuesday that rebel fighters were willing to halt fighting during the holiday, but would respond if attacked.
Sieda says he doubts the regime will honour the ceasefire and that Brahimi does not have "any mechanism to observe the situation".
More than 34,000 people have been killed in the rebellion, which began in March 2011, according to the Observatory.