Trainee doctors in Scotland are being pressured to work extra hours without pay because of staff vacancies, the British Medical Association said today.

Across the UK almost a third of the junior doctors surveyed by the body said they were working on a rota with at least one vacancy.

Dr Alan Robertson, chair of the Scottish Junior Doctors Committee, described hospitals north of the Border where three or more staff were missing from a team.

This, he said, meant the doctors were having to work more frequent night shifts and the day crew were potentially short-handed.

Dr Robertson said: "The knock-on for patients might be an increase in waiting times for procedures or clinics running slower because the usual staff are needed to do a night shift. That will mean patients spend longer waiting.

"I do not think care will be impacted on because dealing with emergencies will always be a priority.

"But the worry is that is increasing as a problem."

According to the BMA, the situation has been caused by changes to the way junior doctors are trained to become consultants.

Under the old system, juniors were recruited to training posts twice a year. The association say people unsuccessful the first time would work as locums until the next opportunity to apply came around. Under the new system - dogged by problems when it launched last year - there is only one entry point, August.

Dr Robertson said: "The way it worked last year those who did not get a training post, left. People who did not get a job went to Australia or New Zealand. We do not have the same group sitting about."

This, and changes to immigration rules restricting employment opportunities, means fewer medical staff are available to act as locums or fill vacancies, according to the BMA. It says the pressures could lead to bullying and harassment of junior doctors.

Dr Robertson said hospitals were running the risk of breaching European working hours legislation which limits junior doctors to a 56-hour working week.

A Scottish Government spokesman said: "There are opportunities for NHS boards to advertise for and appoint junior doctors outwith the annual appointment round."

He added: "Furthermore, we are also considering the possibility of a second formal annual appointment round.

"Remuneration of junior doctors for hours worked is a matter for HR departments at individual NHS boards.

"However, there are rules in place that we would expect to be followed."