Shoppers protesting against high prices have stormed several markets in the Indian city of Calcutta and forced shopkeepers to sell essential goods at cheaper prices.

Police drove out the protesters from two of the city's markets.

Seven people were injured in the clashes.

A BBC correspondent in Calcutta says the prices of onion and tomato are a particular cause of public anger.

He said there were suspicions that politicians had played a role in organising the mobs.