Government accused on waiting times

The target was introduced in the NHS Improvement Plan of 2004, which said that by December 2008, the "maximum wait" for treatment after GP referral "will have been reduced to 18 weeks".

Labour's 2005 manifesto promised "No-one waiting more than 18 weeks from referral to treatment. No hidden waits."

But the Department of Health has confirmed that it is looking at a threshold for meeting the target of 90% of patients who require hospital admission and 95% of those who do not.

New figures show that 76% of outpatients were being treated within 18 weeks in August 2007, along with 56% of inpatients - up from 48% in March this year.

Some 4.2 million patients were waiting for treatment in August and the NHS treated more than 30,000 patients every day during the month.

A Department spokeswoman explained that the thresholds for the 18-week target were set below 100% in order to take account of patients for whom delays are necessary because of the nature of their illness and those who choose to wait longer for personal reasons - perhaps because of a forthcoming holiday.

Last month's Comprehensive Spending Review stated that the target applied only to "clinically appropriate patients who choose to start their treatment within 18 weeks", she pointed out.

But Liberal Democrat health spokesman Norman Lamb said: "It must have been clear from the start that the 18 weeks target wouldn't be suitable for everyone, including those who want to delay their treatment for a clinical or other reason. This seems like yet more shifting sands over waiting times. Why is this key target being changed now? Many people will smell a rat."

Health minister Ben Bradshaw said the "clarification" of the target would provide a buffer to allow clinicians to take account of individual patients' needs. He hailed the figures as a sign the NHS was moving towards its target.