LONDON, Dec 16 (Reuters) - Britain's energy market regulator said it has written to energy companies this week to warn them of potential fines and prosecution if they are found to have manipulated wholesale prices by publishing misleading capacity data.
The letter from Ofgem says concerns have been raised about misleading information regarding available generating capacity, which could raise wholesale prices if there is an expectation of scarce supply in the market.
The UK's biggest energy suppliers are SSE, EDF Energy, Scottish Power, E.ON, RWE and Centrica.
"Generators must ensure that they are providing the most accurate information available on how much electricity their plant can generate and when, based on their experience in running the power stations that they are making available to the market," an Ofgem spokesman told Reuters.
"We have not launched a formal investigation. But we are making it clear that if a generator submits a physical notification that is misleading, clearly this has the potential to be a breach of market rules," he added.
European legislation called REMIT was introduced in 2011 to force energy generators to publish information related to any changes in capacity or use of their production, storage or transmission facilities, such as outages or shutdowns.
British energy companies have been under pressure to improve the information they give about outages or capacity reductions at their plants and Ofgem already raised concerns in 2014.
Ofgem said it sent the letter to all market participants and has not ruled out launching a formal investigation if it has more concerns. (Reporting by Nina Chestney;Editing by Elaine Hardcastle)