LONDON, Feb 2 (Reuters) - France's Thales is working on a plan to buy the cybersecurity business of IT consultancy group Atos, which could be worth about $3 billion, despite expectations of French government opposition to any break-up, sources told Reuters. Thales and its adviser Centerview Partners have approached several private equity firms including Bain Capital to explore a possible joint offer for Atos (ATOS.PA) as part of a deal that would see it broken up, the sources said. Defence group Thales would buy the big data and cybersecurity business, known as BDS, they told Reuters on condition of anonymity....