South Korean convenience stores, which have emerged as a key retail outlet, are moving to accelerate their powerful growth with unconventional merchandise ranging from the latest iPhone to flowers and water purifiers.

Major convenience store brands are introducing new items and services to better cater to a growing number of single households that rely on the retail channel, now visible on almost every street and alleyway across the nation, for most of their shopping.

7-Eleven, which is operated by Lotte affiliate Korea Seven, has introduced five store-in-store flower shops in key commercial districts and plans to expand the number of such stores to 50 by the end of the month.

The convenience store chain has also imported the French underwear brand "Waxx," which sells at a higher price than local brands, for people needing them after overnighters.

GS Retail, an affiliate of conglomerate GS, has teamed up with the tech industry. Consumers can buy bidets, water purifiers and even pre-order an iPhone 6 via a catalog that directly links shoppers with manufacturers.

The company said it has enhanced customer access thanks to its nationwide branch network, while cutting down retail costs for consumers.

The convenience stores, which have dwarfed traditional retail channels in growth, are stepping up efforts to further cement their footing.

Despite lackluster consumption, the convenience store industry saw sales grow 7.5 percent from three months earlier in the second quarter, according to data by the trade ministry.

The on-quarter growth compares with discount chains, department stores and the so-called "super supermarkets," whose sales dipped 2.9 percent, 1.6 percent and 2.5 percent each, the ministry data showed.

But it is also true that the convenience stores are competing against each other as their numbers have ballooned in recent years.

"There are views that quantitative growth has peaked and that the industry is turning into a red ocean. Companies are now turning to quality and boosting profit," said an industry official.

Market watchers said that convenience stores are shifting away from their traditional product mix of instant food and drinks to non-food items to foster loyal customers.

Excluding cigarettes, 7-Eleven saw its portion of non-food products account for 13.6 percent of its overall sales in the January-August period, up from 12.3 percent in 2011. The company plans to raise the portion to 20 percent within five years.

"We are re-identifying our product development strategy to introduce best-selling items in the non-food category," said Oh Jea-yong, who leads Korea Seven's non-food team. (Yonhap)