At least 85 people were killed in 24 hours of Syrian regime air raids on the city of Aleppo, a monitoring group said on Sunday, after 10 days of inconclusive peace talks.
The deaths came as a suicide car bombing in a Hezbollah stronghold across the border in Lebanon killed four people on Saturday, in the latest regional spillover of the conflict.
The Syrian Observatory for Human Rights said regime helicopters hit rebel-held areas of Aleppo with barrels packed with explosives.
The so-called barrel bombs are a controversial weapon, condemned by rights groups as indiscriminate.
"At least 85 people were killed, including 65 civilians, 10 of whom were children," on Saturday, the Observatory said.
Attacks targeted several areas of the city, with 34 killed in the southeastern Tariq Al Bab area alone, among them six children.
Another 22 civilians, including another six children, were killed in the Salhine, Ansari and Marjeh districts, with nine others killed in other parts of the city.
The Britain-based Observatory said 10 jihadists from Al Nusra Front, Al Qaeda's Syrian affiliate, were also killed in a local headquarters in the city.
Ten other deaths in the attacks were recorded but the identities of the dead had not been confirmed.
Once Syria's economic hub, Aleppo is now divided between regime and rebel-held areas, with large swathes of the city devastated by the fighting that began there in mid-2012.
In December, government aircraft launched a sustained blitz on the city that killed hundreds of people, most of them civilians.
Regime forces recently launched an offensive on rebel-held areas in the east of the city, with Defence Minister General Fahd Al Freij visiting the province on Friday.
Quoted by state news agency Sana, he praised the army for its "great victories and their liberation of many areas in Aleppo."
On Sunday, Al Watan newspaper, which is close to the regime, said the army had "cleansed" most of the Karam Al Turab on the eastern outskirts of Aleppo, and Bani Zeid in the north.
The paper said the army planned to take three eastern and three northern neighbourhoods to seize the city in a pincer movement.
It said "vast military operations" were also underway to capture the majority Turkmen town of Zara in central Homs province, near the famed Krak des Chevaliers castle and the Lebanese border.
Opposition sank talks: Syria official
The latest aerial assault came the day after Syrian government and opposition delegations wrapped up peace talks in Geneva.
The 10 days of talks yielded no tangible results and the government team said it was unsure whether it would return to the negotiating table.
On Sunday, Sana carried scathing remarks from deputy foreign minister Faisal Al Moqdad, who accused the opposition of being "mercenaries manipulated by foreign forces."
He said they bore "full responsibility for the lack of results at Geneva because of their refusal to engage on the basis of principles that no Syrian could refuse: the unity of Syria, its independence and its sovereignty."
Syria's UN ambassador, Bashar Al Jaafari, was equally critical of the opposition, accusing them of having "no vision or political programme," Sana said.
Al Watan added, however, that the conflict has "transferred to the political and diplomatic field, which is one that the Syrians know well."
"Syria has a strong army of diplomats and politicians who can defeat all those they face," the paper said.
A top international goal for the talks was greater humanitarian access, particularly in besieged areas like the Old City of Homs.
No deal was forthcoming and Western nations are now planning a UN Security Council resolution on the issue, as well as possibly on the slow pace of a programme to move Syria's chemical weapons out of the country.
More than 136,000 people have been killed since the conflict began in March 2011, and the fighting has raised tensions in neighbouring Lebanon.
On Saturday, a bomb killed four people and injured at least 15 others in the eastern town of Hermel, which is a stronghold of the Shiite movement Hezbollah.
The group has seen its strongholds targeted seven times since it admitted last year that its fighters are battling alongside the Syrian regime.
The attacks have largely killed civilians however.
Al Nusra Front in Lebanon, a group named after the Syrian Al Qaeda affiliate but whose links to its namesake are unclear, claimed the latest attack, saying on Twitter it was a response to Hezbollah involvement in Syria.