Clifford Chance is acting for Olivetti's team of four financial advisers in relation to the computer company's hostile e53bn (£36.5bn) bid for Telecom Italia, in what will be seen as a vindication of the strength of the UK firm's Italian practice.
Clifford Chance is looking after all UK and Italian legal work for Donaldson Lufkin & Jeanrette Securities, Lehman Brothers, Chase Manhattan and Mediobanca.
Alan Inglis, one of the UK's leading banking partners, will be responsible for the UK aspects of the deal, while Nick Wrigley, managing partner of Clifford Chance's Milan office, will head the Italian team.
Inglis and Wrigley were unwilling to talk about the deal, because of its sensitivities, but a spokesman at the firm confirmed that Clifford Chance had been retained by the financial advisers.
Herbert Smith is advising Olivetti in the UK, and will work in conjunction with Italian firm Erede & Associates, Olivetti's corporate adviser in Italy.
Chris Parsons, the partner in charge of Herbert Smith's Italian practice group, which is based in London, said he had a long-standing relationship with Erede & Associates senior partner, Sergio Erede. Parsons said Erede was one of the "top three corporate lawyers in Milan".
Parsons said it was "fantastic" to be involved the biggest European debt financing ever. He said a team of Herbert Smith lawyers had been working on the deal in Milan last week.
Clive Barnard, the head of international finance and banking at Herbert Smith, is heading the firm's Olivetti team, assisted by fellow banking partner Andrew Calderwood. Parsons is being assisted on the corporate side by fellow corporate partner Charles Severs.
Reports from Italy have suggested that Telecom Italia has hired an Italian law firm to examine the possibility of mounting a legal challenge to Olivetti's bid in a regional court.
According to the reports, Telecom Italia has asked the law firm to file a complaint asking the Lazio regional appeals court to block Italian stock regulator Consob's authorisation of the bid on the grounds that it is not legally valid.
Chiomenti Studio Legale, which has offices in Rome, Milan and Turin, is understood to be representing Telecom Italia in its attempts to fight off the hostile bid, but this has not been confirmed.