Hutchison Whampoa, the company that owns Three U.K., is in talks to purchase rival carrier O2 for £9 billion (approx. $13.6 billion), sources say. Three already owns O2's Irish business, but taking over its U.K. arm would make it the largest mobile network in the country.

Hutchison Whampoa, which is owned by Hong Kong tycoon Li Ka-shing, has called upon investment bank UBS AG to investigate the possibility of a takeover, The Sunday Times reports — just weeks after British Telecom turned down the opportunity to merge.

However, the discussions are said to be at a very early stage.

O2 is currently the second-largest carrier in the U.K., beaten only by EE, the parent company of Orange and T-Mobile. A takeover would give Three the opportunity to better compete in the mobile space, and help it leapfrog EE and Vodafone to the largest subscriber base in the country.

O2, which currently sponsors the England rugby team, was recently the subject of interest from BT, but the company later signed a preliminary agreement to acquire EE — the first carrier to offer 4G LTE connectivity in the U.K. — for £12.5 billion (approx. $18.9 billion).