Spanish telecommunications group Telefónica has confirmed the sale of mobile network O2 to Hutchison Whampoa for 10.25 billion, the biggest acquisition yet for the Hong Kong-based group.

The sale is likely to be completed by June 30th and will see O2 combined with Hutchinson’s current mobile network Three, creating the biggest mobile group in the UK if approved by regulators.

It follows the proposed acquisition of EE by BT in November for 12.5 billion, although concerns have been raised about the impact of this deal on competition in the market.