The claims are the latest in a series of rows over staffing

The GMB Union which represents the cleaning staff at the region's biggest hospital, has said workers were put under extreme pressure and some wards had to be left out.

It is the latest in a series of similar accusations that levels of hygiene are not up to scratch.

ISS Mediclean - which supplies the cleaning support staff for the hospital - said that while there were staff off sick, no areas were left uncovered.

The GMB Union alleges that up to 11 wards at Derriford were left with a shortage of cleaning staff over the weekend.

If you do not have sufficient people to do the job you cannot reach the standards and that is clearly what is happening Gary Smith, GMB

Gary Smith, GMB senior organiser in the region, said: "It is absolutely incredible that the contract does not specify a minimum number of staff.

"The contract talks about vague notions of standards.

"But the reality is that if you do not have sufficient people to do the job you cannot reach the standards and that is clearly what is happening."

The NHS Trust which runs Derriford pointed to its model record for cleanliness.

'Good job'

The hospital had been given Green status in the latest national audit of cleanliness and the local community health council had found the hospital's cleanliness was satisfactory.

Spokesman Craig Smith of ISS Mediclean, said: "Our records show that we had about three people sick over the weekend and there was some absenteeism, but that is normal.

"We have more than 300 people working in the cleaning department at Derriford.

"All the areas that we normally clean at weekends were covered."

He added: "The cleaning staff at Derriford do a very good job."

Last week it was revealed that six units at the hospital had failed in-house monitoring for cleanliness.

Intensive cleaning had been carried out and the units were passed 24 hours later.