Syrian government warplanes have dropped barrel bombs on rebel-held areas of Hama province, a human rights monitor says, a day after the US said their use could lead to further American air strikes.
A Syrian military source has denied the report and says the army does not use barrel bombs, which are drums or cylinders packed with explosives and shrapnel that cause indiscriminate destruction on the ground.
The US fired cruise missiles at a Syrian air base last week in response to a poison gas attack on a town in northwestern Syria which Washington says was carried out by government forces.
The government denies responsibility.
The Syrian Observatory for Human Rights said "a number" of barrel bombs had been dropped on the towns of Taybat al-Imam and Soran north of Hama city in an area where rebel groups spearheaded by jihadist factions launched a major offensive in March.
Observatory director Rami Abdulrahman said the number of barrel bombs dropped by government warplanes was relatively small.
White House spokesman Sean Spicer on Monday mentioned barrel bombs alongside poison gas as weapons that were causing "babies and children" to suffer.
"If you gas a baby, if you put a barrel bomb in to innocent people ... you will see a response from this president," he said.
The Syrian military source said: "We do not use these barrels and they do not exist in the Syrian Arab Army."
