Some students do not get the clinical placements they need

The claim was made by the Royal College of Nursing (RCN) after 1,000 student nurses were questioned by Mori.

The survey found more than a third had been left in charge of patients in the absence of registered nurses and doctors.

More than a quarter of first year students said they had been left alone in charge of patients.

The survey was published to mark the start of the RCN's annual conference in Harrogate.

Financial strains

Half of the student nurses questioned said they had considered leaving their course, with one in 10 doing so on a frequent basis.

The pressure and stress of work were the main reasons students gave for this.

Indirect supervision is an entirely appropriate part of clinical learning Department of Health

Financial problems were also raised by more than a quarter of students.

But the vast majority - 89% - said they were still intending to work in the NHS when they had qualified.

Students also complained it was often hard to find the placements they needed as part of their training, with 12% saying they had had placements cancelled..

One in 10 complained they were given a placement which did not involve any direct contact with patients - instead, they might be given a workbook to complete.

Swansea nursing student Stewart Attridge told BBC News Online: "I have been asked to look after a couple of patients. Usually their physical care is not really difficult.

"But student nurses shouldn't officially be doing anything that's unsupervised - even if they are just looking after a couple of patients."

Nurses urge shortages action

RCN president Sylvia Denton said: "Students on clinical placements should never be left alone in charge of patients - it's bad for patients and it's simply wrong to expect students to take responsibility in this way.

"A serious lack of registered nurses to support and guide students is endangering patient care and short-changing these urgently needed new recruits to nursing.

"The government's target of 80,000 more nurses by 2008 is ambitious. But we need to find new ways of supporting student nurses right now.

"Improving student nurses' experiences of education has to be our top priority.

"This means increasing the number of clinical placements, ensuring there are enough registered nurses to mentor students, and a fairer system of funding for all student nurses."

A Department of Health spokeswoman said: "Students should not be put in circumstances which compromise their learning or place patients at risk.

"However, indirect supervision is an entirely appropriate part of clinical learning if the supervising registered nurse judges that the student has achieved a level of knowledge and competence to carry out care without risk to the patient."

Denise Cullingworth, a ward sister at Harrogate Hospital, told BBC News: "We have some excellent auxiliaries, health care assistants and student nurses that do a very, very good job - but they have not got the same level of accountability that we have."