The discontent in Scotland is worse than in other areas of the UK, where 36% of nurses would quit if they could, says the RCN.

Ninety-two per cent of the 400 Scottish registered nurses who took part in the Scotland's Nurses: Attitudes to Working in the NHS survey believed they were badly paid for their work in relation to other professional groups.

Seventy-one per cent thought they were not paid enough for the job they did and only 6% believed they were well paid.

Two-thirds thought they would be paid more for doing less work if they left the profession.

Around half said they were under too much pressure at work and had too much work to do.

Not valued

Margaret Pullen, spokeswoman for the RCN in Scotland, said she did not know why nurses north of the border were more disgruntled than those in the south.

But she said pay was the main reason nurses were considering leaving the profession.

"Unfortunately pay has fallen so far behind comparable professions that we feel we are not being valued.

"But unlike other professions, when nurses leave rather that cause a riot when they have had enough.

"And it is this silent departure that is so worrying."

She added that the public did not appreciate the difference in pay between nurses and other professions.

This meant that nurses were starting from a lower base and needed a bigger percentage increase to bring them in line with similar professions, such as police and social workers.

Nurses' starting salary, at £12,855, is about 20% less than a police constable, 17% less than teachers and 12% less than social workers.

Ms Pullen says the Scottish health minister Sam Galbraith, a former surgeon, is sympathetic to the nurses' case.

But the RCN believes nurses' pay should continue to be decided on a national basis, even when the Scottish Parliament is up and running.

"Otherwise, we could have a system where other UK countries are offering more money to nurses than Scotland and we could have Scottish nurses leaving to work in England," she said.

Health Secretary Frank Dobson gave the clearest indication yet that he is backing moves for a substantial pay rise for nurses in a statement he gave when he visited a children's ward on Christmas Day.

However, he faces a battle with the Treasury which is worried about setting a precedent for others working in the public sector.

Recruitment crisis

But the case for more pay is mounting, with over half of NHS employers saying they are having difficulties recruiting and keeping nurses and managers backing a substantial pay increase.

The Conservatives released a report on Wednesday calling for urgent action over nursing shortages, saying patients' safety was at risk.

Many nurses are moonlighting for agencies to get more money

A report by the Tory backbench health committee on nurse recruitment and retention found that, while there was no overall shortage of qualified nurses, one in four were not working in the NHS.

The report also highlighted the danger of nurses moonlighting for agencies and operating department practitioner nurses who work on standby overnight and then do a full shift the next day.

"In a busy hospital this could mean up to 22 hours' continuous working," it says.

Earlier this week, the Liberal Democrats revealed government statistics showing a big rise in the number of agency nurses being employed by hospitals.

The government has pledged to increase nursing places by 15,000 over the next three years.