Russia's deadly bombing of Syrian hospitals is undoubtedly a war crime, the former international development secretary Andrew Mitchell has said.
Raids blamed on Russia hit at least two hospitals and a school in northern Syria on Monday, killing and wounding dozens of civilians.
"It's certainly a war crime," Mr Mitchell told the 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, but Russia has yet to respond.
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 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.