At least 36 people have been killed in air strikes by Russian and Syrian jets on Islamic State-controlled Deir Ezzor province, a monitor said.
Russia pounded the jihadist group in Syria, firing cruise missiles from warships in the Caspian Sea after President Vladimir Putin vowed retaliation for the bombing of a Russian aircraft in Egypt last month.
At the United Nations, member states called for action against Isis a week after 130 people were killed in Paris terror attacks.
"At least 36 people were killed and dozens more injured in more than 70 raids carried out by Russian and Syrian planes," said Rami Abdel Rahman of the Syrian Observatory for Human Rights monitoring group.
Russia began bombing in Syria in September at the request of President Bashar al-Assad, while a US-led coalition is conducting its own air campaign against Isis.
Putin pledged this week to hunt down and "punish" those behind a bombing that brought down a passenger jet in Egypt, killing all 224 people on board in an attack claimed by Isis.
Russian television showed a man scrawling "For our people!" and "For Paris!" in black pen on bombs minutes before a plane took off from the country's air base in Syria.
Unverified images circulated on the internet of Syria-bound US missiles bearing the handwritten inscription "From Paris with love".
The UN Security Council has backed a French-drafted measure calling on member states to "take all necessary measures" to fight Isis.
The US-led coalition fighting Isis said last week it had destroyed 116 fuel trucks used by the jihadists in eastern Syria.
Isis reportedly makes millions of dollars from oil fields under its control, and the coalition regularly targets oil infrastructure held by the group.