Metro is already widely read by Tube commuters

The way was cleared after the Office of Fair Trading (OFT) reached an agreement with Associated Newspapers, publishers of the free morning paper Metro.

They agreed to give up their exclusive distribution rights on the Tube and the train network after the OFT ruled it could not justify such a deal.

The Metro's circulation is expected to reach 550,000 copies a day this month.

Associated - who also publish the Evening Standard - Express Newspapers, Guardian Newspapers and News International are all thought to be interested in publishing an evening paper and tenders will be accepted from April.

All Londoners will benefit from a wider choice of newspapers being available in the capital Ken Livingstone

London mayor Ken Livingstone, who had been calling for the creation of a free afternoon paper, said he welcomed the decision.

"London Underground are ready to start a tender process for distributing a free afternoon paper on the Tube without delay.

"All Londoners will benefit from a wider choice of newspapers being available in the capital and a new paper will raise substantial additional revenues which will be used to improve services to passengers."

Kevin Beatty, Associated's managing director, said he was pleased the company's proposal had been accepted and put the Metro's success down to its "unrivalled editorial approach".

Vincent Smith, OFT director of competition enforcement, said: "This opens up the market for competitors potentially to provide London commuters with additional afternoon or evening newspapers."