A major inquiry led by former prime minister Gordon Brown has called for international law changes to better protect children trapped in war zones.

Mr Brown says its “unconscionable” that the global community stands by while children are being killed and slammed the “culture of impunity” relating to conflicts in war-torn counties like Yemen, Syria and South Sudan.

In a report to be launched in London on Friday, the inquiry, chaired by Mr Brown, urges global governments to address schools attacks and to stop children being denied humanitarian aid.

“It is unconscionable that the world stands by when children are being attacked in their schools and denied access to vital humanitarian aid,” Mr Brown commented.

“This report sets out an agenda, which every government and every organisation working on children affected by conflict, should act on to end the culture of impunity.”

Gordon BrownFormer prime minister Gordon Brown wants law changes to protect children in war zones (Danny Lawson/PA)

The legal report proposes several reforms, such as developing humanitarian law to prohibit targeting schools and give them the same special protection as hospitals.

It also suggests outlawing the denial of humanitarian assistance in certain circumstances, including where it may lead to the starvation of civilians.

A number of lawyers, activists and academics have thrown their support behind the report, including Save the Children chief executive and former Danish prime minister Helle Thorning-Schmidt.

“In war zones around the world, grave violations of children’s rights continue to be carried out with impunity,” Ms Thorning-Schmidt said.

“This is an important and timely contribution to the debate on how to hold perpetrators to account, and uphold the rules that are designed to keep children safe.”

Former Danish prime minister Helle Thorning-Schmidt Former Danish prime minister Helle Thorning-Schmidt has thrown her support behind the report (Dave Thompson/PA)

The inquiry studied recent war events that have impacted children, including the bombing of a school bus in Yemen and a suicide bombing at an Afghanistan school, both in August.

It also looked at recourse to starvation as a weapon of war in Yemen, where millions of children are on the brink of famine.

The report, written by a legal panel led by Shaheed Fatima QC, was published by Hart.