Leaders of the nursing profession will launch legal action against the health secretary, Patricia Hewitt, today to try to make her rethink plans to "privatise" local health services.

The Royal College of Nursing will apply for judicial review of the decision to contract out district nursing, chiropody, family planning and other community health services provided outside hospitals. The college fears that 250,000 health workers' jobs are at risk from a policy that would reduce the NHS to "little more than a logo", organising services provided by other organisations.

It said last night that it would serve papers on Ms Hewitt today, challenging her "failure to carry out public consultation". The decision is a big step for the RCN, a non-political union that normally works behind the scenes to achieve its ends.

The 300 primary care trusts are local groups which receive about 75% of the total NHS budget. They buy services from hospitals and GPs, but also directly employ nurses and other medical staff.

Sir Nigel Crisp, the NHS chief executive, published plans in July - after parliament broke up for the summer recess - to merge the PCTs and make them shed the direct provider role. The mergers were criticised by many Labour MPs, including former health secretary Alan Milburn.

Ms Hewitt appeared to back down last week after a bruising encounter with MPs at a meeting of the parliamentary Labour party. She said: "District nurses ... and other staff delivering clinical services will continue to be employed by their PCT unless and until the PCT decides otherwise."

But the RCN said she had failed to withdraw Sir Nigel's instruction for PCTs to reduce their provider role "to a minimum" by 2008 and had not given the necessary assurances. The judicial review would focus on her failure to consult rather than the substance of the plan.

Howard Catton, the college's head of policy, said: "We have been under incredible pressure from our members who are deeply concerned and anxious about the future of primary care and their personal futures as well."

The Department of Health said it was disappointed at the RCN's move. A spokeswoman said Sir Nigel had not told PCTs to divest themselves of their provider role, but had asked NHS chief executives to make proposals: "Any changes to either the organisation or function of PCTs will be subject to full local consultation."