Children constituted a quarter of civilian casualties over the last three years in Yemen's war between Iran-backed Houthi rebels and the internationally recognised government, a child relief agency has said.

More than 2,300 children were killed between 2018 and 2020, Save the Children said in a new study. However, the group said the actual toll is likely to be much higher.

"Yemeni children have been living through a horrific and endless nightmare for six years now. Children continue to be killed and injured on a near-daily basis," said the organisation's country director, Xavier Joubert.

Save the Children's report comes on the heels of a Unicef statement issued on Saturday, saying that eight children were killed and 33 wounded this month alone.

Philippe Duamelle, Unicef's representative to Yemen, said the casualties happened in several areas including the provinces of Taiz and Hodeida, where fighting between forces of the internationally recognised government and Houthi rebels has recently intensified.

On Monday, Saudi Arabia offered their Houthi rivals a ceasefire plan that includes the reopening of Sanaa international airport, which has been under siege for almost six years. The Houthis downplayed the offer, claiming it did not provide anything new.

"All parties to the conflict must fully implement a ceasefire as soon as possible," said Mr Joubert. "The ceasefire should be used to work towards a sustainable peace and a political solution to this war - it's the only way to truly end this humanitarian catastrophe."

Like other relief agencies, the London-based Save the Children deplored plummeting funding levels for relief efforts in the war-stricken country. The group said its funds for aid to children in Yemen has dropped by more than 40% compared to last year.

"If the UN's predictions are correct, the worst famine in decades could kill hundreds of thousands of children. We must do everything we can to prevent this from happening," said president and CEO Janti Soeripto.

Yemen has been convulsed by civil war since 2014 when the Houthis took control of the capital Sanaa and much of country's north, forcing the government of President Abed Rabbo Mansour Hadi to flee to the south, then to Saudi Arabia. A Saudi-led coalition, backed at the time by the US, entered the war months later to try to restore Mr Hadi to power.

Now mired in stalemate, the war has killed about 130,000 people - including more than 12,000 civilians - and spawned the world's worst humanitarian crisis in a country that was already the Arab world's most impoverished nation.