Telefonica sells UK phone operator O2 to Hutchison Whampoa for over about $15 billion

European cell phone operator Telefonica says it has reached an agreement to sell its British business, O2, to Hong Kong conglomerate Hutchison Whampoa for 10.25 billion pounds ($15.24 billion).

Spain-based Telefonica said Tuesday that the deal was reached after due diligence over O2 was completed. It added that the completion of the transaction is subject to regulatory approval.

Hutchison's owner, Hong Kong billionaire Li Ka-shing, announced in January the plans to buy O2. The conglomerate already owns British mobile operator Three.

Li is Asia's richest individual, with a fortune estimated by Forbes at about $35 billion. His sprawling ports-to-retail global conglomerate operates in more than 50 countries.