A spokesperson for Ofcom told Brand Republic that Rapture had lodged a complaint about BSkyB's EPG pricing, but was unable to make any further comment while the case was being investigated.
BSkyB could be liable to face a fine under European Union law, which could run into millions, for failing to act in a "fair, reasonable and non-discriminatory way".
A spokesperson for BSkyB dismissed Rapture's claims and told Brand Republic: "We believe that Rapture's case is without merit and completely unfounded.
"We have always treated Rapture in a fair manner, and we look forward to presenting our evidence to Ofcom in due course."
Last year, Ofcom launched another investigation into BSkyB about the amount it charges broadcasters to carry channels after ITV called on the regulator to intervene following a long-running price dispute.
Sky charges ITV £17m a year for access to its EPG service. Under a new deal, Sky is proposing that ITV pay between £13m and £17m to ensure viewers in different areas pick up the correct news and programming dedicated to their ITV region. ITV insisted that Sky is overcharging the network and the fee should be more like the £4m rate the BBC pays.
Rapture claims that BSkyB previously charged a much lower fee to feature on its electronic programming guide, which allows Sky users to access schedule information and channels.
The channel added that the £76,800 a year EPG fee charged by BSkyB is "not cost related", and it is in the process of submitting evidence to Ofcom about its treatment from the broadcaster.
David Henry, managing director of Rapture, said: "I am confident that with the evidence we have presented, Ofcom will have no further option but to find in our favour."
He added that Rapture wanted a fairer system where "a dominant competitor can not abuse its position in an anti-competitive way".
Ofcom confirmed that Rapture's complaint was being investigated, but that there were no further details at present.
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