Patients in Oxfordshire are waiting longer than the national average for a range of medical tests.

Figures published by the Government show that in April, patients in the county were waiting for 7,201 diagnostic tests, including MRI and CT scans which provide electronic images of abnormalities inside the body.

In 3,027 cases - 42 per cent - patients were kept waiting 13 weeks or longer.

By comparison, nationally just 25 per cent of cases took longer than 13 weeks from referral to test.

Some of the longest delays in Oxfordshire were for hearing tests, which made up 44 per cent of the outstanding total at the end of April.

Figures showed 2,690 of the 3,219 audiology tests were taking 13 to 25 weeks. In more than 2,000 cases, patients had to wait 26 weeks or longer.

The Government said data for 15 of the most common diagnostic tests, which will be published monthly from now on, would help the NHS meet its target of delivering all diagnostic tests within six weeks of GP referral by 2008.

The figures showed the national average wait for any of the 15 tests, which also include barium meals, endoscopies and non-obstetric ultrasound scans, was seven weeks.

Health Minister Andy Burnham said: "The NHS is at last identifying and tackling these waiting lists.

"By revealing them, we have also identified the progress that NHS staff have already made in reducing waiting times for the 630 million tests they carry out every year."

To further speed up access to diagnostic tests, Mr Burnham also announced that from April next year, any patients waiting longer than 13 weeks for a CT or MRI scan would be offered an appointment at an alternative hospital or clinic.

Oliver Francis, a spokesman for Oxford Radcliffe Hospitals NHS Trust, said: "Our diagnostic waits differ across specialities.

"CT waiting times average five weeks in Oxford and seven weeks at the Horton.

"For ultrasound examinations, waiting times are five weeks at the Horton and seven weeks in Oxford.

"For MRI examinations, excluding referrals for neuroradiology, the wait is two to three weeks.

"However, because MRI has become the preferred diagnostic tool for neurological imaging, there is currently a high level of demand on MRI brain scans at the RI, with the average wait being 15 weeks.

"There are no waits for general radiography referrals such as chest x-ray, as there is a walk-in service for these."

Mr Francis said audiology tests were not currently covered by the 13-week wait limit.

A recent shift from analogue to digital hearing devices had also resulted in an increased demand on services.