A number of the UK's largest retailers including John Lewis, Debenhams and House of Fraser have been accused of fixing the price of sports bras.

According to the Office of Fair Trading (OFT), DB Apparel UK, which supplies the Shock Absorber brand of sports bras, entered nine anti-competitive agreements with John Lewis, Debenhams and House of Fraser between 2008 and 2011.

The agreements allegedly aimed to increase the retail prices of Shock Absorber bras in each of the department stores. The brand held a 15% share of the sports bra market over the period.

The OFT alleges that the agreements amounted to resale price maintenance, a serious infringement of competition law. Retail price maintenance occurs when a supplier specifies the resale price of a product to retailers and retailers agree to the price set.

"The OFT takes allegations of price-fixing seriously. Resale price maintenance limits competition between retailers and can lead to consumers paying higher prices," said OFT senior director of services, infrastructure and public markets Ann Pope.

Businesses found to have infringed the Competition Act could be fined up to 10% of their worldwide turnover.

Responding to the allegations, DB Apparel said: "We reject any allegations by the OFT that we have entered into any agreement or understanding with retailers as to their retail prices of our products. We have been transparent with UK authorities since the beginning of this process and will continue to defend ourselves vigorously in this investigation."

Debenhams added that it "disputes these provisional findings of the OFT but is not in a position to comment further at this stage".

Meanwhile, House of Fraser said it is "co-operating fully with the Office of Fair Trading and the ongoing investigation and will respond accordingly. We are confident that we have been operating within all laws and regulations and are very supportive of any initiative which ensures pricing policies are fair for our customers."

A spokesperson for John Lewis added: "John Lewis always strives to operate within the law and comply with regulations. We are fully cooperating with the OFT and will respond in due course."