Twenty human rights groups urged UN chief Ban Ki-moon on Wednesday to put a Saudi Arabia-led military coalition back on a UN blacklist for killing and maiming children in Yemen because the evidence against it was “overwhelming.”

Twenty human rights groups urged UN chief Ban Ki-moon on Wednesday to put a Saudi Arabia-led military coalition back on a UN blacklist for killing and maiming children in Yemen because the evidence against it was “overwhelming.”

The UN removed the coalition from its annual blacklist on Monday pending a joint review by the pair, after Riyadh, a key UN donor, had threatened to cut off funding, according to diplomatic sources.

The letter to Ban on Wednesday, signed by groups including Human Rights Watch, Amnesty International and Oxfam, criticized Ban, who steps down at the end of the year, saying he capitulated to Saudi Arabia and tainted his legacy, Reuters news agency reported.

“If the Saudi-led Coalition wants to be removed from the list, it should stop killing and maiming children and bombing schools and hospitals in Yemen — the violations for which it was listed,” the groups wrote.

The UN report, released last Thursday, said the coalition was responsible for 60% of child deaths and injuries in Yemen last year, killing 510 and wounding 667, and half the attacks on schools and hospitals.

“The responsibility of the Saudi-led coalition for grave violations against children in many of these attacks is not in doubt,” the rights groups wrote.

“The evidence of grave violations against children in Yemen by the Saudi-led Coalition is overwhelming.”

Yemen has been since March 26, 2015 under brutal aggression by Saudi-led coalition.

Thousands have been martyred and injured in the attack, with the vast majority of them are civilians.

Riyadh launched the attack on Yemen in a bid to restore power to fugitive Hadi who is a close ally to Saudi Arabia.