Meanwhile, a Turkish-backed opposition group says Moscow and the Syrian regime are trying to wrest control of two major highways in their last enclave in the north-west of the country.
Air strikes by Syrian regime ally Russia on Sunday forced the closure of two hospitals and also damaged a third one in the opposition and rebel-held Syrian province of Idlib, a war monitor said. Idlib falls in the demilitarised zone agreed upon by Russia and Turkey in 2018.
The strikes came as eight civilians were killed in bombardment by the regime and Russia across the north-western province, the Britain-based Syrian Observatory for Human Rights said.
Idlib and other adjacent territories of Syria held by the opposition and rebels have faced intensifying bombardment in the past month.
On Sunday, air strikes hit a hospital in Kafranbel and another located underground on the outskirts of Hass.
The raids were blamed on Russia by the Observatory.
An AFP cameraman filmed the two facilities hit by strikes.
"The hospital in Kafranbel is out of order. The patients were transferred to other facilities in the region," Observatory director Rami Abdel Rahman said, adding one civilian was killed.
Hass and Hama hospitals
In Hass, air strikes blamed on Russia halted services at an underground hospital, Syria Relief and Development, a non-governmental organisation that runs the facility, said.
"The hospital... is out of order because of the raids," said Ubaida Dandush, who works for the NGO.
The facility had been evacuated shortly before the bombardments, he said, thanks to alerts from a warning system set up to analyse the flight paths of warplanes.
Footage filmed by the AFP cameraman showed a white cloud rising over farmland where the hospital is located.
The Observatory said the facility had been put "out of service" because of "bombing by Russian aircraft".
It said a third hospital in the north of Hama province had also been hit by Russian strikes. The Observatory added that it had not been able to verify the extent of the damage.
The war monitor says it determines whose planes carried out strikes according to type, location, flight patterns and munitions.
On Sunday, Syrian state news agency SANA reported the death of a civilian in a rocket attack by "terrorist groups" on a regime-held town near Idlib province.
A regime forces source cited by SANA accused "terrorist organisations in Idlib of planning attacks" against government areas and army positions.
Idlib is under the administrative control of Hayat Tahrir al-Sham (HTS), which is dominated by a faction previously known as the Nusra Front before it renounced ties to Al Qaeda.
Russia's Idlib assault meant to take highways - FSA
A Turkish-backed opposition group said on Monday that Moscow and the Syrian regime were trying to wrest control of two major highways in their last enclave in the north-west of the country in a bid to shore up Syria's sanction-hit economy.
The sixth day of the campaign by government forces saw heavy aerial attacks targeting the city of Jisr al Shughour and the al Ghab plain, as well as the towns of al Latamenah and Maarat al Numan in the south of Idlib province, the group said.
Taking those areas would bring the regime leader Bashar al Assad close to regaining control over the strategic M5 and M4 highways from Aleppo to Hama and Latakia on the Mediterranean coast, two of Syria's most important pre-war arteries.
"The shelling and aerial strikes have increased in intensity and ferocity and the area hit has widened with more intensity," Naji Mustafa of the Turkey-backed National Liberation Front (NLF) group told Reuters.
Opening the commercial and passenger routes through Idlib province would reassert the state's control over a fragmented economy that sprung up during eight years of conflict and now facing US and EU sanctions, economic experts say.
Russian President Vladimir Putin said last week that he did not rule out a full-scale assault on "militants" in Idlib province, after Russian officials publicly questioned how far they would continue to tolerate "jihadist" control.
The loss of opposition control over the highways would mean the loss of a financial asset for the opposition and the rebels, as well as be a sign of their weakening hold on their last enclave.
Russia and Turkey in September inked a buffer zone deal to prevent a massive regime offensive on the Idlib region, near the Turkish border.
But the region of some three million people has come under increasing bombardment since HTS took full control of it in January.
The civil war in Syria has killed more than 370,000 people and displaced millions since it began with the bloody repression of anti-government protests in 2011.