* Deal to sell Brazil towers may be reached in weeks - sources
* Telecom Italia aims to fetch 900 mln euros - sources (Adds details, context)
By Danilo Masoni and Guillermo Parra-Bernal
MILAN/SAO PAULO, Oct 23 (Reuters) - Telecom Italia is in advanced talks to sell the mobile phone towers of its Brazilian unit TIM Participacoes (TIM Brasil) and could agree a deal in weeks, three people with direct knowledge of the situation told Reuters.
Telecom Italia is aiming to raise 900 million euros ($1.1 billion) from the sale of TIM Brasil's towers but is unlikely to fetch the full ticket, as bids have come in at between 500 million and 600 million euros, the sources said.
The sale of the Brazilian towers would provide Telecom Italia cash that could help it boost investments to compete against Telefonica, America Movil and Grupo Oi.
Telecom Italia Chief Executive Marco Patuano put the towers up for sale in November when he unveiled a 4 billion euro plan to cut debt and help fund much-needed investments.
One of the sources said American Tower Corp and Cell Site Solutions (CSS), a company backed by Goldman Sachs, were left in the race, adding a deal could see the asset being split between them.
Telecom Italia, American Tower and CSS declined to comment.
One issue in the talks is that buyers are concerned mergers in the Brazilian market could bring down the number of mobile operators to three from four, reducing the value of the asset, according to one of the sources.
The agreement will also have to be approved by the local competition watchdog which could take four or five months.
Analysts and bankers are speculating about a possible merger between TIM Brasil and Oi, a smaller rival of TIM Brasil in mobile telephony. Such an operation, they say, makes industrial sense but first needs political backing - which still remains uncertain ahead of a presidential ballot on Oct. 26.
TIM Brasil, which tried unsuccessfully to acquire Brazilian broadband business GVT from France's Vivendi earlier this year, has hired Banco Bradesco to evaluate strategic alternatives, while in August Oi mandated Grupo BTG Pactual to study a potential takeover of TIM.
Cooling expectations of a deal, Patuano said last week TIM Brasil could skip potential mergers and acquisitions for five years without losing market share. (Additional reporting by Silvia Aloisi in Milan; Editing by Stephen Jewkes and David Holmes)