Premier stores are to hold a scratch card giveaway that owner Booker claims is the biggest promotion even run by a symbol group.

The wholesaler says it is laying on the promotion to celebrate Premier passing the 2,500 store mark ­closing the gap on Spar, the UK's biggest convenience retailer, with 2,600 stores.

The 2,507 Premier retailers will give away more than a million prizes in the promotion, which will run from 14 April to 11 May.

Shoppers spending more than £5 will be given a scratch card that offers a one-in-three chance of winning a prize.

The prizes include six 'golden tickets' with a £2,500 cash reward, while the rest of the prizes are in the form of key grocery products, including major branded soft drink and confectionery lines.

These will be given to retailers at the same time as the scratch cards and are available for instant redemption. Booker and suppliers have invested £1m in the scheme £750,000 to support the cost of the prizes and £250,000 for advertising.

"This promotion should increase spend for our customers and increase footfall and frequency of visit," said retail sales director Steve Fox.

Premier said it had signed up 409 stores in the past 12 months.