Telecoms giant BT is in “highly preliminary” talks about buying mobile phone network O2.

The group said it had received “expressions of interest” from shareholders in two network operators, one of which is O2, about a possible transaction in which it would acquire their UK mobile business.

BT said: “All discussions are at a highly preliminary stage and there can be no certainty that any transaction will occur.”

The group said it was responding to press speculation about a deal with O2’s owner Telefonica, which bought the business, formerly known as BT Cellnet, after it was spun off in 2001.

It is understood that the other operator involved is EE, owned by Orange and Deutsche Telekom.

BT said: “We continue to develop our own plans for providing enhanced mobile services to business and consumer customers, in line with our previous announcements.

“We remain confident of delivering on these plans and have also been exploring ways of accelerating them, including assessing the merits of an acquisition of a mobile network operator in the UK.

“We have received expressions of interest from shareholders in two UK mobile network operators, of which one is O2, about a possible transaction in which BT would acquire their UK mobile business.

“All discussions are at a highly preliminary stage and there can be no certainty that any transaction will occur.

“A further announcement will be made if and when appropriate.”

In July, BT took its first big step back into the mobile phone market as it launched a new business service aimed at delivering fixed line and mobile calls to the same handset.

It is already planning to launch a mobile phone business for the wider public by the end of the current financial year to the end of March.

The latest move comes as BT is also engaged in a TV football war with Sky, as it tries to lure broadband customers with free Premier League broadcasts. It has also brought Champions League rights.

Telecoms operators are increasingly focused on moving into “quad play” - bundling together landline, mobile, internet and TV services for customers.