At least 27 people, including six children, were killed when government warplanes targeted several areas in Homs province, including the towns of Talbiseh and Zaafaraneh, the UK-based Syrian Observatory for Human Rights reported on Wednesday.
The death toll is still expected to rise, the observatory added, because several others have been severely injured. Some bodies remained under the rubble.
In another development, government helicopters dropped at least 26 barrel bombs on Western Ghouta outside of the capital Damascus, with no death toll reported yet, the observatory said.
Russia authorises use of troops
Russia's upper house of parliament has granted President Vladimir Putin authorisation to deploy the country's air force to Syria, according to the head of presidential administration.
Sergey Ivanov said on Wednesday that the Federation Council backed Putin's request for approval unanimously.
"The operation's military goal is exclusively air support of the Syrian armed forces in their fight against ISIL," he said, referring to the Islamic State of Iraq and the Levant group fighting against President Bashar al-Assad.
The Syrian conflict, which began as a peaceful protest in 2011, has led to at least 250,000 deaths, according to the United Nations.
More than half of Syria's prewar population of 22.4 million has been internally displaced or fled abroad.
Source: Al Jazeera and agencies