The NHS is improving but there is still more work to be done, its chief executive told a conference in Birmingham yesterday.

Sir Nigel Crisp told delegates at the NHS Confederation's conference, being held at the International Convention Centre, that they still faced "some formidable challenges".

Among the issues facing public sector health workers is the ever-present need to cut spending and offer better "value for money".

Five years after the NHS Plan was first introduced in 2000 to improve all facets of the service, Sir Nigel said noticeable changes had been made.

"The first external confirmation that we're changing came from the private health sector," he said.

"For years their business plans had been based on growth as patients left the NHS, but this growth has stopped as the NHS has improved.

" We have had the interesting spectacle, over the past 18 months or so, of seeing the private sector selling hospitals as they have had to revise their outdated plans."

Speaking ahead of Health Secretary Patricia Hewitt, who will address the conference today, Sir Nigel underlined her earlier message that the NHS would not face a "wholesale reorganisation".

But he added: "While the number and role of strategic health authorities may not be looked at during this part of the process, over time I believe we will see fewer of them.

"As more hospital trusts achieve foundation trust status and primary care trusts start to take a bigger role, the need for so many SHAs will be lost."

When asked about a Labour manifesto pledge to take £250 million out of management costs, in order to offer "value for money", Sir Nigel said the NHS must be more cost-effective.