At least 115 children have been killed and 172 maimed in the violence raging in Yemen since Saudi-led air strikes began on March 26, the UN children's agency said Friday.

"We believe that these are conservative figures," UNICEF spokesman Christophe Boulierac told reporters in Geneva, saying at least 64 of the children killed between March 26 and April 20 were victims of air strikes.

The UN agency said another 26 children had been killed by unexploded ordnance and mines, 19 by gunshots, three by shelling and three by "unverified causes related to the conflict".

Seventy-one of the children died in the north of the country, UNICEF said.

The World Health Organization said Thursday the overall death toll in Yemen had topped 1,000, and the UN's human rights agency said Friday at least 551 of the people who died were civilians.

UNICEF meanwhile said that since March 26, at least 140 children had been recruited by armed groups.

"There are hundreds of thousands of children in Yemen who continue to live in the most dangerous circumstances, many waking up scared in the middle of the night to the sounds of bombing and gunfire," UNICEF representative in Yemen Julien Harneis said in a statement.

"The number of child casualties shows clearly how devastating this conflict continues to be for the country's children," he said.