At least seven people have been killed and 85 injured in flash flooding in Yemen this month, the UN said Tuesday, as the coronavirus threat also looms over the war-torn nation.

Yemen announced its first case of COVID-19 on April 10, and aid organisations have warned that its health system -- all but collapsed since a conflict between the government and Huthi rebels broke out in 2014 -- is ill equipped to handle the crisis.

"Heavy rains and flooding across northern governorates, including Marib, in mid-April led to casualties and damaged property and sites for internally displaced persons," the UN humanitarian coordination agency OCHA said.

"Initial information indicated that seven people -- five women and two children -- were killed in the flooding and another 85 people were injured, including seven who were seriously injured and hospitalised."

The rebel-held capital Sanaa and districts in the same governorate "have been badly affected", it added.

Storms also hit other provinces, including Ibb, Hajjah and Marib -- which is the government's last northern stronghold and currently the conflict's "centre of gravity".

The UN special envoy for Yemen, Martin Griffiths, said last week that progress was being made towards a ceasefire after calls for a pause to face the coronavirus threat, although military activities were continuing "on a number of fronts".

An estimated 24 million Yemenis -- more than 80 percent of the population -- depend on some form of humanitarian or protection assistance for survival, according to the UN.

More than three million people are displaced, many in camps that are especially vulnerable to disease.