By Robin Paxton and Maria Plis

MOSCOW (Reuters) - X5 Retail Group (PJPq.L: Quote, Profile, Research), the Russian food retailer controlled by billionaire Mikhail Fridman, said Friday it would buy Karusel hypermarkets for up to $970 million as it seeks a bigger share of Russia's consumer boom.

Retailers are cashing in on Russia's growing consumer spending power after nearly a decade of economic growth powered by record-high oil prices.

X5 said it would pay $920-970 million in a deal it expects to close by July 1 as the leader in supermarkets and discount retail stores adds to its network of hypermarkets.

"We plan to change the whole landscape of the sector, creating a national retail champion with a big advantage over competitors," Chief Executive Lev Khasis told reporters on a conference call.

X5, which owns the popular Perekryostok and Pyatyorochka stores, said it would become Russia's fourth biggest hypermarket operator in sales and floor space after the acquisition.

Germany's Metro AG (MEOG.DE: Quote, Profile, Research) and French-owned Auchan [AUCH.UL] occupy the leading positions.

X5 combined with Karusel will account for almost a quarter of the total sales of Russia's top 10 food retailers.

The exact value of its acquisition of 100 percent of Karusel owner Formata Holding B.V. will depend on the value of Karusel's land and real estate under construction, X5 said in a statement.