A woman is suing the NHS after she was refused permission to seek hip replacement surgery in France in a test case that could determine the right of British patients to go abroad for treatment.

In what is believed to be the first legal action of its kind, Yvonne Watts, 72, is suing her local NHS primary care trust for the right to be treated straight away by doctors on the Continent under new European Union rules.

Ms Watts, of Queen's Park, Bedford, has to use a wheelchair and is in constant pain but has been told by local health managers that she may have to wait up to a year for a hip replacement on the NHS.

Her daughters, Julie and Pauline, contacted La Louvière hospital in Lille, and found that surgeons there could do the operation without delay. La Louvière was the hospital used to treat 200 patients from Britain facing long waits in a high-profile government initiative last summer.

Under a European Court of Justice ruling last year, all patients in the EU have the right to be referred elsewhere if they face "undue delay" in getting treatment in their own country.

Last week, EU ministers agreed a formal declaration enshrining the right to be treated anywhere in the union. Patients will be able to travel to other countries for treatment if their own country cannot provide it "within a time limit which is medically justifiable".

That phrase was interpreted by Bedford Primary Care Trust as being within one year. Margaret Stockham, chief executive, said yesterday: "The definition of 'undue delay' is down to member countries. The UK definition, which we have checked with the Department of Health, is a delay beyond the maximum waiting time laid down in the NHS plan. For this lady at this time that would be 12 months."

The legal firm Leigh, Day & Co, which is acting for Ms Watts, argues that the trust has misinterpreted "undue delay".