* Offers 18 euros/shr or 256 million euros for remaining stake
* Deal expected to offer operational benefits, flexibility
* Swisscom to pay dividend in 2011 (Recasts, adds share price, details)
By Deepa Babington and Nicola Leske
ROME/FRANKFURT, Sept 8 (Reuters) - Swiss phone company Swisscom AG plans an offer to buy the remaining Fastweb shares it does not own for 256 million euros, taking advantage of the Italian unit's battered share price to gain full control.
Swisscom said on Wednesday it would offer 18 euros in cash for the remaining 18 percent of Fastweb once it gets approval from Italian market regulator Consob.
Fastweb shares had surged 33 percent to 17.9 euros by 1011 GMT in Milan while Swisscom was unchanged at 397.7 Swiss francs in Vienna.
Analysts say the buyout would allow the Swiss operator to enjoy greater flexibility in creating partnerships and simplify operational matters like reporting and listing requirements as well as offering cost savings over the medium term.
The offer represents a 34.6 percent premium to Fastweb's closing price of 13.41 on Tuesday, but is lower than the stock's 12-month high of 21.1 euros struck last October and well below the 47 euros per share price Swisscom paid in 2007 for its current stake.
Analysts said the price was reasonable, if not particularly generous.
"The premium seems enough to avoid the risk that the price rises above that of the bid," said Oriana Cardani, an analyst with Centrobanca. She had a target of 16 euros on the stock.
Fastweb shares have dropped 28 percent over the past year, hit by a money-laundering probe that led to the arrest of its billionaire founder Silvio Scaglia.
Both Fastweb and Scaglia have denied any wrongdoing, saying they are the victims of fraud.
The company took a provision of 70 million euros to cover risk, including those stemming from the probe and revised its 2009 results to a net loss.
Ratings agency Standard & Poor's said its ratings on Swisscom were unchanged and it viewed the deal as mildly positive in the medium term, since it would end dividend payouts to minority shareholders and the delisting of Fastweb could offer cost savings.
Swisscom bought a majority stake in Fastweb in 2007 to counter lacklustre growth at home, where it faces price pressures and increasing competition.
Swisscom said it would finance the buyout itself of via an existing credit line. It also said it would pay a dividend in 2011 at least equivalent to the amount the previous year and would have the financial means for any future deals.
Swisscom hinted last week that a buyout could be on the cards, saying the move could be a good investment but would consume part of its limited financial capacity. ($1=.7846 Euro) (Additional reporting by Stefano Rebaudo in Milan; Editing by Michael Shields and Karen Foster)