Tony Blair said yesterday that pressures on the NHS this winter could develop into a crisis - but only if public expectations were raised too high.

Tony Blair said yesterday that pressures on the NHS this winter could develop into a crisis - but only if public expectations were raised too high.

In a plea for patience from the public and medical staff, the Prime Minister launched a charm offensive to win support for the Government's four-year NHS plan but said results could not be delivered overnight. Mr Blair also took the opportunity, ahead of an election widely expected next year, to hammer home his opposition to tax relief on private health insurance and challenged doctors to give up the right to private practice early in their careers.

He admitted to an audience of senior hospital consultants meeting at the Royal College of Surgeons to mark the college's 200th anniversary that the Government had underestimated NHS problems when it took office two years ago.

The NHS plan, published in July, would deliver a huge boost in staff and resources, with thousands of extra doctors, nurses and beds - but it would take "time, patience and effort. In the short term problems are bound to persist," Mr Blair said. "We cannot just conjure up out of nowhere the extra heart and cancer specialists we need. It takes years to train them."

In several unscripted departures from the printed version of his speech, he referred repeatedly to the need to look years rather than months ahead. He said he was worried that winter pressures were now operating "practically the whole year round". And he took a sideswipe at sections of the media who, he said, were waiting to exploit the problems.

"We have to explain to the public that this is a long-term plan. I think the first test will come around the winter, when there will be parts of the media determined to promote a crisis. I know there will be problems, but let us not get the whole thing completely out of perspective. We need to work together."

Doctors, who have been keen to demonstrate their support for the NHS plan, while preparing to do battle over the detail, received the Prime Minister with warm applause yesterday. During a question and answer session at the end of Mr Blair's speech, no one challenged him on the most contentious issue: plans to restrict consultants' private practice.

He set out in uncompromising terms the choice facing the profession given the desire, of patients and doctors alike, for a consultant-led service. Either they would have to accept a new junior consultant grade that would lead to full consultant status after a few years - an option few in the profession want - or they should accept that the role of consultants must be adapted in the first few years after appointment.

"If we are to make best use of the extra consultant numbers ... we have to try to use them flexibly," Mr Blair said.

Under the plan, newly appointed consultants would be expected to devote themselves fully to the NHS for the first seven years of their careers. Doctors' leaders have opposed the proposal on the basis that in no other profession are employees restricted from using their free time as they wish. They have also said they will consider legal action under the Human Rights Act.