Humanitarian organisation Medecins Sans Frontieres (MSF) says one of its hospitals in Syria has been hit by airstrikes.

MSF said two people were killed and six injured when the makeshift facility was hit while several wounded were arriving for treatment.

An attack was launched on Erbin, one of the besieged zones east of Damascus on Thursday afternoon local time, MSF said, during which two missiles exploded just outside the hospital.

It follows a US air strike last month that "mistakenly struck" an MSF hospital in Afghanistan, killing 30 people.

"MSF is appalled that again a health structure and staff are targeted after responding to provide life-saving treatment to wounded victims of an indiscriminate bombing campaign," MSF director of operations Brice de le Vingne said.

It is not yet clear whether the bombs came from the American-led coalition, Russia or some other group.

Yesterday the United States Defence Department said it would redact the report into last month's hospital bombing in Afghanistan, meaning some details as to why a hospital was targeted may remain secret.