Royal Mail has revealed that it has set aside £18m to cover a French fine and legal costs related to antitrust rules.

The UK delivery service, that only became a public company a year ago, said one of its French subsidiaries, GLS, is under the French authority's spotlight, and it is preparing for any fines and legal costs a negative verdict would entail.

"Royal Mail announces that it has entered into a settlement agreement with the French competition authority (Autorité de la Concurrence) in respect of the alleged breaches of antitrust laws by one of its subsidiaries, GLS France, during the period before the end of 2010," said the group in a statement.

"Royal Mail confirms that, whilst a settlement has been agreed in principle, the French regulator is continuing its investigation. By agreeing to settle and provide compliance commitments now, Royal Mail will benefit from a reduction to any fine."

The group added that it made the financial provision of £18m (€23m, $29m) in its financial statements for the half year ended 28 September 2014, which comprises of £12m in respect of the current estimate of any fine and £6m to cover estimated legal costs associated with the investigation and the costs of the compliance commitments.

The Royal Mail is not the only delivery service under regulatory scrutiny as La Poste, DHL/Deutsche Post, FedEx, TNT Express, and SNCF, are also under investigation by the French authorities.