Telefonica is working on a joint offer to take over TIM Participacoes and break up the local wireless unit of Telecom Italia also known as TIM Brasil, an Italian daily said on Friday citing reliable sources. Brazils antitrust watchdog last month told the Spanish telecoms group to either sell its interest in TIM Brasil or seek a new partner for its market-leading Vivo mobile business. Il Sole 24 Ore newspaper said Telefonica, which partly owns TIM Brasil via its 15 percent stake in Telecom Italia, is looking to set up an investment vehicle with its two main rivals on the Brazilian mobile market to buy the unit and break it up. The two rivals are Carlos Slims America Movil, owner of mobile operator Claro, and Brazils Oi. Telecom Italia was not immediately available for comment.