The Syrian military and non-jihadist rebel forces had agreed to a temporary truce around the city of Aleppo, following pressure from the US and Russia.
Air strike was carried out at Kamouna refugee camp in rebel-held northern Syria.The strike comes a day after the extension of a truce was confirmed.
At least 28 people are reported to have been killed in an air strike on a refugee camp in rebel-held northern Syria, monitors say.
Images on social media showed tents destroyed at the Kamouna camp near Sarmada in Idlib province, close to the Turkish border.
Some reports say the attack was by Syrian or Russian warplanes but this has not been confirmed.
