Russia announced a 12-month extension of its grain export ban yesterday, raising fears about a return to the food shortages and riots of 2007-08 which spread through developing countries dependent on imports.

The announcement by Vladimir Putin came as the United Nations’ Food and Agriculture Organisation called an emergency meeting to discuss the wheat shortage, and riots in Mozambique left seven dead.

The unrest in Maputo, in which 280 people were also injured, followed the government’s decision to raise bread prices by 30 per cent. Police opened fire on demonstrators after thousands turned out to protest against the price hikes, burning tyres and looting food warehouses.

Although agricultural officials and traders insist that wheat and other crop supplies are more abundant than in 2007-08, officials fear the deadly Mozambique riots could be replicated.

The 2007-08 food shortages, the most severe in 30 years, set off riots in countries from Bangladesh to Mexico, and helped to trigger the collapse of governments in Haiti and Madagascar.

The Russian announcement extended an export ban first announced last month until late December 2011, sending wheat and other cereals prices to near a two-year high.

The FAO said that “the concern about a possible repeat of the 2007-08 food crisis” had resulted in “an enormous number” of inquiries from member countries. “The purpose of holding this meeting is for exporting and importing countries to engage.”

Russia is traditionally the world’s fourth-largest wheat exporter, and the export ban has already forced importers in the Middle East and North Africa, the biggest buyers, to seek supplies in Europe and the US.

Mr Putin said Moscow could “only consider lifting the export ban after next year’s crop has been harvested and we have clarity on the grain balances”. He added that the decision to extend the ban was intended to “end unnecessary anxiety and to ensure a stable and predict-able business environment for market participants”.

“This is quite serious,” said Abdolreza Abbassian, of the FAO in Rome. “Two years in a row without Russian exports creates quite a disturbance.” Dan Manternach, chief wheat economist at Doane Agricultural Services in St Louis, added: “This is a wake-up call for importing nations about the reliability of Russia.”