Big rises in fuel prices have been announced in Zimbabwe.

The cost of petrol has gone up sixty-seven per cent -- the biggest jump since independence twenty years ago -- while the cost of paraffin, widely used for lighting, cooking and heating, has more than trebled.

The National Oil Company of Zimbabwe said the increases were due to the slump in the value of the Zimbabwean dollar.

Basic food prices were raised about twenty per cent in early October and 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.