UPDATE 1-Tel. Italia could sell T. Argentina stake-letter

* Antitrust decisions prompt sale consideration

* Hires Credit Suisse to examine strategic options

* Stake worth about $300 million

(Adds details, share price)

MILAN, July 6 (Reuters) - Telecom Italia SpA (TLIT.MI) could sell its stake in Telecom Argentina SA TECB.BA because of an antitrust probe, Italy's dominant phone company said in a letter released on Monday.

Telecom Italia's main aim is to keep its stake in Telecom Argentina, but antitrust decisions "have induced Telecom Italia to evaluate alternative solutions, among which are the possible sale of the aforesaid stake", board secretary Vincenzo Covelli said in the letter to Telecom Argentina dated July 3.

Telecom Argentina has a market capitalisation of $1.1 billion, according to Reuters data.

Telecom Italia has made no decision about a possible sale of its stake in Sofora Telecomunicaciones SA, the holding company that controls Telecom Argentina, Covelli said. Telecom Italia owns half of Sofora.

Telecom Italia has hired Credit Suisse Group AG (CSGN.VX) to examine strategic alternatives for the Argentine market, including potential buyers, he said.

Argentine regulators have been investigating a possible telecoms monopoly because one of Telecom Italia's shareholders, Spain's Telefonica SA (TEF.MC), runs local operator Telefonica de Argentina (TEA2.BA).

Shares in Telecom Italia closed down 1.3 percent at 0.9905 euros. The DJ Stoxx telecoms index .SXKP was up 0.2 percent. (Reporting by Paola Arosio; Writing by Ian Simpson; Editing by David Holmes)