The government has withheld £13.3m in payments to supplier EDS because of continuing problems with the Child Support Agency (CSA) computer system.

But Work and Pensions Secretary Alan Johnson has rejected MPs? demands for a deadline for either making the system work or abandoning it.

Replying to a report from the Commons Work and Pensions Committee(Computing, 27 January), Johnson said there is ?much more work needed to bring the agency?s performance to an acceptable level?, but claimed there are signs of improvement.

He said the system is serving 620,000 new cases, and that the government ?does not intend to work up detailed abandonment plans at this stage? because an independent review says the problems can be solved.

Work and Pensions Committee chairman Sir Archy Kirkwood said: ?The absence of a confirmed date for acceptable performance by the CSA, while understandable, is a major shortcoming in the government?s response.?

The CSA system developed by EDS went live in March 2003 ? 11 months late and £29m over budget. But because of technical problems, hundreds of thousands of people are still on the old system waiting for their cases to be transferred.