Three people have been killed and more than 30 injured in a stampede at a supermarket sale in China.

French chain Carrefour, in the city of Chongqing

The shop was offering large discounts on cooking oil. A crowd that had been waiting hours for the store to open then burst through the doors.

State media Xinhua said bargain-hunters were crushed underfoot in a sale to mark the 10th anniversary of the store's opening in the south-western city.

At least seven of the injured are in a serious condition, Xinhua said.

Cooking oil prices have soared by more than a third in the past year.

In Chongqing, Carrefour was reportedly offering 20% off rapeseed oil.

Carrefour, which is the world's second-biggest retailer, has been keen to expand in China as it booms and recently opened its 101st hypermarket in the country.

Three die in China sale stampede