The sale of eight Trinity Mirror titles to Dunfermline Press Ltd could be referred to the Competition Commission.

The sale of the Observer and Express series, in Berkshire, has given the Scottish firm control over the only two local newspapers in the Slough, Windsor and Eton area.

The OFT has asked Dunfermline Press Ltd to come up with a series of "satisfactory undertakings" which would address concerns over a possible restriction in competition.

Once these have been finalised, the OFT will then decide whether the sale should be referred to the Competition Commission.

Simon Pritchard, the OFT's senior director of mergers, said: "In an obvious case like this, our aim will still be to spare the costs of reference [to the Commission] while restoring the benefits of competition lost by the merger.

"We owe it to consumers to make clear-cut remedies the preferred exception to reference in all suitable cases.

"Equally, UK business has strongly encouraged the OFT to solve cases via undertakings in lieu, and clarity on this issue helps companies plan merger activity with the right incentives in mind."

The OFT believes that Dunfermline Press may lack complete monopoly power over local advertising because of internet competition but may still be able to raise prices and reduce service.

It says this is because the merger has eliminated close competition between the Observer and Express series of newspapers.