Isoft, the struggling healthcare software company, confirmed late Friday night that it would start legal proceedings against Computer Sciences Corporation, its partner in the £12.4bn National Health Service IT programme, after the US group continued to block the bid by Australia’s IBA Health to take over the UK group.

In a strongly worded statement, Isoft added that it was concerned that CSC’s wider interests “may be influencing its conduct” on the matter, pointing out that CSC had been considering a possible offer for Isoft since November 2006.