Around 5,000 people demonstrated in the flood-riven southern Algerian town of Ghardaia on Friday to demand urgent aid after flash floods killed 33 residents, witnesses said.

Police broke up the rally before the crowd could reach the municipal headquarters, witnesses told AFP. The protesters demanded basic food supplies and equipment to help search for survivors or bodies buried in the rubble.

The death toll in Ghardaia climbed to three Friday as aid workers battled to help hundreds of homeless and the army was deployed to prevent looting, state radio said.

The floods had left 50 people injured and made about a thousand homeless around the historic town, a UN World Heritage site at the entrance to the Algerian desert in the M'Zab Valley, state radio said.

The Algerian government on Friday unblocked aid for victims, said the minister for national solidarity, Djamel Ould Abbas, as cited by APS agency.

Prime Minister Ahmed Ouyahia gave "strict orders for victims of the natural catastrophe to be taken care of by releasing" unrestricted credit, the minister said.

Hundreds of volunteers, Red Crescent workers and scouts were helping the homeless. The radio said the water level was eight metres (26 feet) high in some parts of the town, some 600 kilometres (370 miles) south of the capital Algiers.

In and around Ghardaia, those who had escaped the worst of the flooding helped their less fortunate neighbours, offering shelter and hot meals to those left homeless by the flash floods.

Tunisian President Zine El Abindine Ben Ali on Tuesday sent his "sincere condolences" and "strong feelings of sympathy and compassion" to Algerian counterpart Abdelaziz Bouteflika.

Interior Minister Noureddine Yazid Zerhouni said the floods are the worst for a century, while locals on Friday reported sweeping damage.

"Hundreds of houses have been destroyed but thousands have been damaged and are uninhabitable in the area," said a resident of El-Gaba, a village near Ghardaia, speaking in front of his ravaged home.

"It's unimaginable, a real catastrophe," added another, confirming that four people had died in the vicinity and three others were missing.

Another shocked resident said all the homes damaged by the waters would effectively have to be rebuilt.

Gas and electricity supplies have been partially revived, but there was an acute shortage of basic goods and medicines -- most of which had been damaged due to the flooding.

The interior ministry sent tents, generators, and 400 tonnes of food aid to the region. The authorities also requisitioned two sports halls, where they installed 890 tents and 1,500 camp beds for those made homeless by the rains.

Several parts of Algeria were lashed by heavy rain including Djelfa -- midway between Ghardaia and Algiers -- where two people died.

Flooding in the Algiers region in 2001 killed more than 800 people and caused considerable damage.