The charity Christian Aid has joined calls for a special commission to be set up under the Geneva Conventions to investigate the US bombing of a Médecins Sans Frontières (MSF) hospital in Afghanistan.
It killed 12 medical staff and ten patients and 24 people are still missing.
An airstrike six days ago in Kunduz, northern Afghanistan, has left thousands of locals trapped without any hospital care.
Many are saying that this attack was in breach of international law - which bans the targeting of hospitals.
Christian Aid is getting behind MSF and calling for the International Humanitarian Fact-Finding Commission to launch an investigation.
Nick Guttmann, Christian Aid's Humanitarian Head said: "The Commission has been ineffectual up until now because of a lack of political will on the part of signatory states.
"Meanwhile health facilities are routinely attacked in conflicts world-wide such as those in Syria, Iraq, Yemen and Afghanistan, resulting in the deaths of medical staff and patients alike.
"Frequently the intensity of a conflict, or perversely, the fact that only local staff are involved, means such attacks fail to make headlines.
"That wasn't the case here and we urge the UK and the EU to press for the commission to launch a rigorous enquiry to demonstrate that it's ready, willing and able to uphold international humanitarian law, and help bring those responsible to account.
"Every signatory state to the Geneva Conventions is bound to "respect" and "ensure respect" to that law to protect civilians, yet non-combatants make up 80-90 per cent of the victims of modern armed conflicts.
"This shows an impunity surrounding violations of the law which greatly diminishes faith in the Geneva Conventions and respect for basic humanitarian principles. It also obstructs the provision of aid to populations in need, and must be countered."