Algiers: Algerian authorities on Sunday vowed to punish those responsible for nationwide food riots in which at least four people were reported killed and more than 800 injured.

Warning that troublemakers "will not go unpunished," Interior Minister Dahou Ould Kablia was quoted as saying in press reports that around 1,000 protestors had been arrested, many of them minors, during the weekend disturbances.

He said they would appear before judges beginning on Sunday.

Out of the 826 people injured, the minister said 763 were police.

The latest victim was a young man shot dead late Saturday in the Tiaret area, located 340 kilometres (200 miles) west of Algiers as he tried, along with his father, to protect their bar from troublemakers, several sources said Sunday.

Kablia announced Saturday that three youths were killed in M'sila, Tipaza and Boumerdes, three towns where the unrest had broken out.

Some of those arrested face charges of arson and "injuries resulting in death", lawyer Rachid Menadi told AFP.

In a bid to curb the price rises, some as high as 30 per cent since January 1, the government on Saturday announced a temporary 41 per cent cut in customs duties and taxes on sugar and food oils.

On Sunday, calm appeared to return to all cities and towns which had been hit by rioting.

In Algiers, stores began to reopen, although the lower taxes on sugar and food oils announced by the government have yet to take effect.

"I paid 15 dinars (0.15 euros) for a croissant which I normally buy for 10 dinars and the baker explained that that this was because of the higher price of sugar," said an electrician who identified hismelf only as Murad.

The unrest in Algeria, which is still under a state of emergency following a civil war with Islamist extremists in the 1990s, comes as the UN Food and Agriculture Organisation (FAO) food price index hit its highest level since it began in 1990.

The rioting was carried out by youths born in the 1990s, when bloody clashes between security forces and Islamists left tens of thousands of people dead, said an executive in a public works firm located in a a restive city district.

"We are talking of a generation that has grown accustomed to violence and has no point of reference," he added.

In Borj el Bahri, a district east of Algiers, the rioters, mainly teenagers, attacked schools, the public library and the post office.

About 75 per cent of Algerians are under the age of 30, and 20 per cent of youths are unemployed, according to the International Monetary Fund. Many are well-qualified but cannot find work.

Most of the country's political parties have called for immediate measures to tackle the crisis.

The National Liberation Front (FLN), the leading member of the country's ruling coalition, called in a statement issued Saturday for "concrete measures to fight against the leap in prices and to protect the purchasing power" of Algerians.

"Controls must be imposed on prices. Speculation and monopoly must be fought against," the party said, while condemning "theft and pillaging" during the riots.

The General Union of Algerian Workers and Trade Minister Mustapha Benbada have accused producers and wholesalers of inflating prices ahead of new measures requiring them to systematically bill for their goods.

In Tunisia, the opposition said at least 20 people were killed in weekend clashes which have also been sparked by high food prices and youth unemployment.