Russia's bombing of Syrian hospitals is undoubtedly a war crime, the former international development secretary Andrew Mitchell has claimed.
Moscow has denied being responsible for an attack on a facility in Idlib province run by Medecins Sans Frontieres.
But former cabinet minister Mr Mitchell said the Russians were guilty of breaking international laws.
"It's certainly a war crime," the ex-cabinet minister Mr Mitchell told BBC Radio 4's Today programme.
"The Russian Air Force has now hit 30 hospitals in Syria of which only one is in an Isil (Islamic State) area.
"Everyone knew this was a Medecins Sans Frontieres (Doctors Without Borders) hospital and undoubtedly this is a breach of the international law and the Russians are guilty of that."
Turkey and France have also agreed that the attacks constitute war crimes.
Mr Mitchell said nothing could be done to immediately challenge Russia.
"There is effectively nothing we can do at the moment but they can be held to account in the future," the Tory MP said.
"For Russia's reputation in the future and its role in the UN this has a very significant effect."
The Britain-based Syrian Observatory for Human Rights said Russian warplanes targeted the hospital in Idlib province, destroying it and killing nine people.
But a spokesman for Russian president Vladimir Putin dismissed the report and told journalists to rely on official announcements from the Syrian government.
The air strikes came days after Russia and other world powers agreed to bring about a pause in fighting next week to allow for the delivery of humanitarian aid.
However, Syrian president Bashar al-Assad has cast doubt on the ceasefire, warning in a televised address that such a truce did not mean all parties would put down their weapons.