Porters at Oxford's largest hospital are threatening to walk out of wards because of poor pay and conditions.

The workers at the John Radcliffe claim they do not get paid for extra hours and have pledged not to do overtime until the dispute is resolved.

Their action could cause problems at the Headington-based hospital and NHS managers said they could be left in a serious situation without the porters.

Doctors and nurses rely on the team of porters to transport patients to scans, X-rays and between wards. They also deliver vital specimen samples to laboratories around the hospital. But they claim they do not get paid enough to live on in Oxford.

They also claim their sub-contracting employers Mediclean should pay them for overtime.

Porters are paid 4.30 an hour and receive 83p extra an hour for doing night duty.

Many of them have not been given uniforms and are forced to wear jeans and T-shirts around the hospital.

One porter, who would not be named, said: "We do important jobs but we are treated like skivvies. Although we have spoken to our bosses about it for months, nothing has been done.

"All Mediclean seems to care about is profit. It would be better if we were employed by the hospital."

The porters have been in talks with Mediclean this week but angry that nothing has been done have agreed on an overtime ban in protest.

The spokesman said: "We don't see why we should do anything extra. And if we walk out, we all will except for theatre porters, where obviously people's lives are at risk."

Mediclean would not comment on the situation.

Oxford Radcliffe Hospitals spokesman Megan Turmezei said: "Obviously the dispute is between the workers and Mediclean and we have no problems with them, but we monitor their performance regularly.

"If the porters did walk out, Mediclean would have to find appropriate ways to replace them. Portering is crucial to the smooth running of the JR."