Drought-hit Morocco often faces severe weather, but Sunday's flooding in Safi is already the deadliest such disaster in at least a decade.

A muddy torrent swept cars and bins from the streets of the town, which is around 300 kilometres (186 miles) south of the capital Rabat.

National weather forecaster the General Directorate of Meteorology (DGM) warned that more thunderstorms were likely over the next three days in several areas, including Safi.

Seven survivors were still being treated at the town's Mohammed V hospital, with two of them in intensive care, according to updated figures from local officials.

Schools have been closed for at least three days, as mud and debris clog the streets.

"The water overwhelmed us. We couldn't sleep all night. We lost everything, even my children's textbooks," mother of six Hanane Nasreddine told AFP, her voice trembling.

Nezha El Meghouari said she had had only moments to escape her home.

"I've lost all my clothes. Only my neighbour gave me some to cover myself. I have nothing left. I've lost everything," she said.

At least 70 homes and businesses in the historic town centre were flooded, and 55-year-old shopkeeper Abdelkader Mezraoui said the retail economy had been devastated.

"Jewellery store owners have lost all their stock... and the same goes for clothing store owners," he said, calling for official compensation to save businesses.

Safi is known as a centre for arts and crafts, particularly terracotta pottery, and its streets were left littered with smashed bowls and tajines.

The Moroccan prosecutor's office announced the opening of an investigation to determine if anyone bore responsibility for the extent of the damage, according to official news agency MAP.

- Intense storms -

Speaking to parliament, Prime Minister Aziz Akhannouch said "37 millimetres (1.5 inches) of rain fell in a short period of time and hit the historic Bab Chabaa district (in Safi), which is crossed by a river, causing the deaths of numerous merchants and workers".

Late on Sunday, rescuer Azzedine Kattane told AFP about the strong "psychological impact of the tragedy" in light of the large number of victims.

As the waters receded, they left behind a landscape of mud and overturned cars. Onlookers watched Civil Protection units and local residents working to clear debris.

Morocco is struggling with a severe drought for the seventh consecutive year, while last year was the North African kingdom's hottest on record.

Climate change has made storms more intense, because a warmer atmosphere holds more moisture and warmer seas can turbocharge weather systems.

Flash floods killed hundreds in Morocco in 1995 and scores in 2002.