text: In a Scrubbing Up column for the BBC News, Nigel Edwards, chief executive of the Nuffield Trust, says the hundreds of millions of pounds it will cost could be better spent elsewhere.
  He said other areas for investment include improving out-of-hospital services and tackling sepsis.
  But Health Secretary Jeremy Hunt told the BBC doctors agreed with him.
  His claims come despite criticism from the British Medical Association, which has argued he has not given enough detail about the plans or explained how it will be funded.
  The BMA has been given until next Friday to agree to discuss the plans with the government.
  Plans for a seven-day NHS have provoked a bitter row between the government and doctors' representatives.
  Ministers argue thousands of people die every year because there is not the same level of service at weekends as during the week.
  The British Medical Association, which represents doctors, says the government has failed to set out what its policy means in practice, and what it will cost.
  It points out that many doctors already work at weekends.
  In an exclusive interview and article for the BBC's "Scrubbing Up" column, the Nuffield Trusts's chief executive, Nigel Edwards, says a seven-day NHS is a good aspiration.
  But he argues the health service is in a world of "tough trade-offs", with many hospitals only managing to meet their current commitments by running up deficits.
  He concludes the policy is likely to cost hundreds of millions of pounds, and suggests - in the current climate - there are better ways of spending the money.
  In his column, he says: "NHS policy is largely made by middle-aged, middle-class men and women who commute long distances into London and Leeds."
  Mr Edwards added: "I think one compelling priority would be to try and shorten the time that patients stay in hospital.
  "A seven-day-service helps a little with that but actually this is more about investing in community services and getting the decision-processes in hospitals a lot slicker. And we could do that, probably, more easily".
  He says there may also be benefits from focusing on individual conditions.
  "Another area would be sepsis, which has a very large toll of mortality, probably much more significant than seems to be associated with seven-day working.
  "Putting in some measures to spot that early and to intervene in a more effective way would have a big effect on people."
  Health Secretary Jeremy Hunt has defended the push for a seven-day NHS. He acknowledged there may be "upfront costs" of hundreds of millions of pounds, but he told the BBC there may also be similar levels of savings because of improved discharge from hospital.
  He also argued the government was investing in other areas such as the new meningitis B vaccine, new cancer drugs and dementia.
  And he insisted there was strong support in the health service for the seven-day plan.
  "For doctors who are totally passionate that the NHS should offer the best and safest care anywhere in the world, the knowledge that thousands of people die every year because we don't offer the same level of service at weekend as we do in the weeks is something that really worries them."
  The chief executive of the Sepsis Trust, Dr Ron Daniels, welcomed the proposed emphasis on tackling the problem, which kills an estimated 37,000 people every year in the UK.
  "Reducing deaths from sepsis is not rocket science but there's been relatively little investment in dealing with the problem.
  "A stronger approach to tackling sepsis would be the quickest win towards saving lives and would require much less investment than a move to full seven-day services in the NHS."
target: Ministers insist there is strong support for their seven-day NHS plans as experts challenge the policy.