Snow fell on Algiers Thursday, a rare event, on the third day of a vicious cold snap that has hit the northern regions, made worse by winds of more than 70 kilometres (45 miles) an hour.

The government meanwhile has warned against further unrest, with Prime Minister Ahmed Ouyahia saying Monday that "order will be maintained and the law strictly applied."

On Tuesday six people arrested in rioting at Birine, near Djelfa, 270 kilometres south of the capital, on January 17, were given eight months' jail for public order offences and fined 5,000 dinars (50 euros, 65 dollars).

Hundreds of residents of Birine had poured into the streets of the little town the day after the government decided to raise the price of a cylinder of butane gas despite parliamentary opposition.

They sacked and burned public buildings, erected road blocks and set light to tyres, press reports said. Police intervened with teargas to disperse the demonstrators.

On January 23 it was the turn of Tiaret, 340 kilometres west of Algiers, Annaba and Guelma, 600 and 530 kilometres to the east respectively, and Maghnia in eastern Kabylie, near the frontier with Morocco.

Again demonstrators blocked roads, sacked public buildings, overturned vehicles, and blocked highways to protest against higher transport prices caused by the increase in fuel costs.

In December parliament opposed a plan to raise the prices of butane gas and fuel oil, the only available sources of energy in Algeria's remote mountain regions and high plateaus.

But the government went ahead and did it anyway, putting up the cost of a gas cylinder by nearly 18 percent, from 170 to 200 dinars, and oil by almost nine percent.

Angry residents speaking on radio said that not only had the authorities forced up prices but they were incapable of ensuring adequate supplies, leading to the creation of a black market.

As a result they were paying up to 350 dinars a cylinder of gas, compared with a guaranteed minimum wage of 10,000 dinars and an unemployment rate of some 20 percent.

Ouyahia said the price rises were necessary to ensure the profitability and continued existence of the state-owned fuel producer.

Algeria's exports of oil and gas brought in more than 31 billion dollars (24 billion euros) in 2004, Energy Minister Chakib Khelil said last month.

Since massive unrest in Kabylie in spring 2001, sparked by hostility between ethnic Berber tribespeople and the government, rioting has become a common way for people to vent their feelings against local authorities and attract the attention of Algiers.