German mobile operator O2 plans to end its roaming agreement with Deutsche Telekom unit T-mobile at year end, O2's German head told a German newspaper.

We now have a very strong network and will terminate the national roaming agreement with Deutsche Telekom at the end of the year, Rene Schuster, head of Telefonica's German O2 unit, told weekly Euro am Sonntag newspaper.

Analysts estimate the savings to O2 at around 150-170 million euros ($223-253 million), the paper said.

Roaming occurs when a mobile phone owner uses a service network different to the owner's home network.