Computer Sciences Corporation (CSC) is to oppose the £132.3m offer IBA Health has made for NHS software supplier iSoft.

The services giant has step-in rights over iSoft's development of its 'Lorenzo' hospital administration software for the £12bn National Programme for NHS IT, of which CSC is a major contractor.

CSC is yet to provide reasons for its opposition to the deal.

'ISoft has received a letter from CSC indicating that they will not consent to the transaction,' said an IBA Health spokesman. 'We need to go back to iSoft and CSC and seek clarification as to what the issues are and how we work our way through.'

iSoft has faced on-going problems including a series of profit warnings, losses of £344m in August last year and a Financial Services Authority investigation into possible breaches of accounting standards.

The firm was contracted to both CSC and Accenture to provide Lorenzo to NPfIT. And when Accenture walked away from its two NPfIT deals in October, CSC, which was already responsible for one area, took over.

As part of a Memorandum of Understanding with iSoft, CSC guaranteed the ailing company a certain amount of business under the NPfIT deals, but also introduced a 'step-in' clause that says CSC can take over development of Lorenzo if iSoft is not performing adequately.

CSC's opposition pushed iSoft shares down 9.5 pence to 41.25p on the London market this morning.

ISoft and IBA said they were seeking clarification from CSC.