The price of paraffin, widely used for lighting, cooking and heating by the poor, has more than quadrupled, from 1.82 Zimbabwean dollars to 8.11 dollars (US$0.22) a litre.

Petrol prices have gone up by 67%, to 9.67 Zimbabwe dollars (US$0.26) a litre.

The National Oil Company of Zimbabwe (Noczim), the sole importer of petroleum products, said that a slump in the Zimbabwean currency against the dollar had forced the increase.

"The continued slide in the exchange rate has had adverse effects on about 90% of the country's elements which are denominated in foreign currency," Noczim said.

The exceptionally high jump in the price of paraffin is to make up for its previous exemption from fuel price increases, the company said.

Currency slumps

The Zimbabwean dollar has lost more than 60% of its value against major international currencies in the last few months, which has been blamed on poor economic management, foreign and domestic speculation and the impact of the decline in Asian economies on developing countries.

Correspondents say the increases in fuel prices are expected to have a knock-on effect throughout the whole economy, further raising transportation fares and delivery, manufacturing and food production costs.

In recent months, the price of Zimbabwe's staple food, corn meal, has already risen by 40%. Earlier this month, bread prices rose by more than 30%.

It is feared that the latest price rises could lead to more unrest in this southern African country, where the trade unions have been expressing concern over falling living standards for months.

Teachers and municipal workers have staged strikes over unpaid wages and at least five people were killed in food riots earlier this year.