The strikes, thought to be Russian, hit the hospital in the northwestern province of Idlib late Wednesday, the Britain-based Syrian Observatory for Human Rights war monitor said.

The Observatory, which relies on sources inside Syria for its information, says it determines whose planes carry out raids according to type, location, flight patterns and munitions used.

Inside the hospital in the village of Hass on Thursday, boxes of medicine lay scattered on the floor while part of a wall had collapsed onto a bed and medical equipment, an AFP correspondent said.

The strikes come after the regime in December last year launched an offensive on Idlib, which is dominated by an alliance led by Al-Qaeda's former Syrian affiliate.

"The hospital was the last functional one in all of southeast Idlib," Observatory head Rami Abdel Rahman said.

"In two weeks, seven hospitals and medical clinics have been hit in Idlib in strikes by the regime or its Russian ally," he said, adding that a blood bank was also hit.

After another strike on a hospital in Idlib last week, Doctors Without Borders (MSF) expressed alarm at the repeated targeting of healthcare centres.

"Civilian areas -- specifically healthcare facilities -- are being hit in northwestern Syria," said Omar Ahmed Abenza, MSF head of mission for northwestern Syria, after the strike on the area of Mishmishan.

"The strikes, despite their regularity during the seven years long conflict, are currently at an intensity that should be a landmark, another wake-up call," he said.

The bombardment of medical facilities has a "terrible knock-on effect", he said, with fearful staff at other facilities reducing their services after each strike.

"The result is more people in greater need, with fewer health services open and available."

Jihadists and rebels overran Idlib in 2015, but since then hardliners have expanded their control and the influence of mainstream rebels has shrunk drastically.

Some 2.5 million people, including more than one million displaced Syrians, live in the province.

More than 340,000 people have been killed since Syria's conflict started in 2011 with the brutal repression of anti-government protests.