All four deaths occurred in Moknine in the Monastir governorate of the North African country, where "two people were swept away by floodwaters, while a woman drowned in her home", said Khalil Mechri, a civil defence spokesman.

Abderazak Rahal, head of forecasting at the National Institute of Meteorology (INM), told AFP some Tunisian regions had not seen so much rain since 1950.

"We have recorded exceptional amounts of rainfall for the month of January," Rahal said, with the regions of Monastir, Nabeul and greater Tunis the hardest hit.

Authorities said classes would be suspended on Wednesday in public and private schools and universities in 15 of the country's 24 governorates because of the weather.

Striking images of cars stranded as torrents of water rushed through streets circulated widely on social media.

"It hasn't stopped raining since last night," Tunis resident Mostafa Riyahi told AFP on Tuesday.

"At first, I didn't pay attention to it, there were only a few small leaks. But when I got out of bed, I found my feet in water."

Transportation has also disrupted in several areas.

The Tunisian army was taking part in rescue operations, a defence ministry source told AFP on condition of anonymity.

Mahrez Ghannouchi, another INM official, said in a Facebook post the situation was "critical" in some regions.

The tourist village of Sidi Bou Said, on the outskirts of Tunis, has recorded 206 millimetres of rain since Monday evening, according to the INM.

- Poorly maintained infrastructure -

The latest rainfall has proved record-breaking, but Tunisian streets often flood after heavy downpours, largely because of the state of the country's infrastructure.

Drainage and stormwater networks are often old and poorly maintained, particularly in rapidly expanding urban areas, with waste sometimes clogging the system.

Rapid urbanisation of some areas has also led to less rainwater being absorbed into the ground, increasing runoff.

The dramatic deluge comes as Tunisia grapples with a seven-year drought, worsened by climate change and marked by a sharp decline in water reserves in dams nationwide.

The country has seen severe water stress, particularly affecting agriculture and drinking water supplies, with cuts imposed in several regions during the summer.

In neighbouring Algeria, several regions have also been hit by massive downpours and floods.

Algerian civil defence authorities said they had recovered the body of a man in his sixties who died in flooding in the western province of Relizane.