Doctors Without Borders (MSF) called on Thursday for an independent inquiry into an air strike that killed 25 people at an MSF hospital in northern Syria.
MSF says it was probable that the air strike was conducted by Syrian regime forces or those of its allies.
International president of MSF, Dr. Joanne Liu, said that accounts from surviving staff at the hospital in the province of Idlib led it to believe that Syrian and Russian forces were involved.
"We say probability because we don't have more facts than the accounts from our staff," Liu told a news briefing. "The only thing predominantly in the region” are the Syrian regime forces and their allies.
MSF also said that it had not provided the hospitals; GPS coordinates to the regime and Russia, at the request of its staff.
Dozens of health facilities hit last year
MSF announced on Thursday that more than 60 MSF sponsored health facilities in Syria were hit in attacks last year, with many of them completely destroyed.
An MSF report stresses Syria’s health infrastructure "has been decimated," with frequent air strikes and bombardment of hospitals and clinics in violation of international law.
The MSF report said 63 facilities it supports in north, northwestern, and central Syria had been hit in a total of 93 aerial and shelling attacks throughout 2015, with 12 completely destroyed.
A total of 83 health workers at the facilities were killed or wounded in the attacks, the group said.
The London-based Syrian Observatory for Human Rights (SOHR) said the aerial assault was conducted by Russian warplanes.
Since Russia began its intervention in the civil war in Syria to support the regime its air strikes have killed at least 1,800 civilians and caused millions of others to flee.