The United Nations said Tuesday that thousands of families across war-torn Yemen have been hit by torrential rains and deadly floods since mid-April that destroyed homes and shelters.

"Initial reports indicate some 3,730 families [22,380 people] have been affected by the rains and flooding, the majority of whom are internally displaced people," the UN humanitarian agency OCHA said.

"Intensified rainfall over the past few days is causing damage to infrastructure, destroying homes and shelter and causing deaths and injuries."

On Monday, the government said four people were killed in flash floods in the historic city of Tarim in the central province of Hadramawt, and the UN cited reports of three deaths elsewhere in Yemen.

AFP footage showed city streets in Tarim flooded and its famed mud-brick buildings in ruins, with cars and motorcycles buried under mud and debris.

OCHA said flooding also caused extensive damage in the provinces of Aden, Abyan, Daleh, Lahj, Hadramawt, Marib and Taez.

Dozens of people are killed every year across Yemen in flash floods.

Fierce storms have added to the woes of the conflict-ridden country.

The UN says Yemen is suffering the world's worst humanitarian crisis as a years-long war rumbles on, with over 4 million people displaced and two-thirds of its 30-million population dependent on aid.

Tens of thousands of people have been killed and millions pushed to the brink of famine in the conflict between the government — supported by a Saudi-led military coalition — and Iran-backed Houthi rebels that is now in its seventh year.