UPDATE 1-Italy's Impregilo signs 450 mln euro highway deal

* Deal to generate 2.4 billion euros in revs over 50 years

* Shares accelerate gains after deal announced

(Adds details, share price)

MILAN, March 24 (Reuters) - A group led by Italian builder Impregilo SpA (IPGI.MI) has signed an accord to build and operate a new toll highway around Milan, Impregilo said on Tuesday.

Impregilo will get 450 million euros ($613 million) for its part in building the highway and 2.4 billion euros of revenues over 50 years to manage it, it said in a statement.

Its partners in the deal include Atlantia (ATL.MI) unit Autostrade per l'Italia. The construction part of the accord is worth an overall 1.5 billion euros.

Impregilo shares added to gains after the deal was announced. By 1547 GMT they were up 3 percent at 1.92 euros, while the DJ Stoxx construction and building materials index .SXOP was down 0.53 percent. (Reporting by Danilo Masoni, editing by Will Waterman) ($1=.7337 Euro)