Dozens of air strikes and shelling hit parts of the last swathe of Syrian territory still held by rebels on Friday, according to rebels, rescue workers and a war monitoring group, in a possible prelude to a full-scale government offensive.
The UK-based Syrian Observatory for Human Rights said dozens of strikes from helicopters and war planes had hit parts of Hama, Idlib and Aleppo provinces, killing at least 29 people.
The three areas in northwest Syria are the last major ones still in the hands of fighters seeking to overthrow President Bashar al-Assad, whose forces recaptured the area around Damascus and the southwest earlier this year.
Syrian state news agency SANA reported that the Syrian army carried out operations against "terrorist groups", its term for the rebels, in northern Hama countryside, destroying several of their headquarters and killing and wounding an unspecified number.
The Observatory said Friday's air strikes were the first to hit the area in almost a month and could be seen as "preparation for an offensive". It has said additional government forces have been arriving this week for a possible attack in an area to the southwest of the opposition territory.
The United Nations worries that such an offensive could force 2.5 million people towards the Turkish border.