America Movil SAB, owned by Mexican billionaire Carlos Slim, will launch a €7.2-billion ($9.6-billion) bid for the part of Dutch telecom company Royal KPN NV it does not already own, in a challenge to a rival offer for KPN’s prized German mobile group E-Plus.

Movil’s €2.40 per share bid for KPN announced today offers a 20 per cent premium to yesterday’s closing price, valuing the company’s stock at around €10.3 billion, and the 70 per cent it doesn’t already own at €7.2 billion.

The news of the approach sent KPN shares 17 per cent higher to €2.34 in Amsterdam.

The offer price is miles above the €1.60 KPN’s shares were trading at in mid-July before Movil’s arch-rival, Telefonica SA, announced plans to buy E-Plus from KPN for around €8.1 billion.

The Telefonica deal was backed by KPN’s management, but most analysts believe Slim wanted E-Plus for himself. E-Plus has a 15 per cent stake in the German market that would be near-impossible to build from scratch.

Movil said it initially invested in KPN two years ago to improve its geographical diversity. Now it wants a controlling stake “to facilitate greater operational cooperation and co-ordination between the two companies’’.

KPN spokesman Ward Snijders had said yesterday that the company is “studying” the America Movil bid.

The Telefonica deal for E-Plus must still be approved by KPN shareholders, including Movil, and it is expected to receive scrutiny from European regulators as it would combine Germany’s third and fourth largest mobile providers.

Movil said today it is still pondering which way to vote on the deal in spite of launching the bid for the rest of KPN.

It said that its offer for KPN will be dependent on receiving at least 50 per cent of KPN’s shares and there being “no competing transactions having been announced or made by any party’’.