NHS staff have lodged more than 150 complaints about bullying in a year.

By far the largest number of allegations were raised in the capital's health board, NHS Lothian, where an action plan to tackle bullying was launched in the wake of a scandal two years ago.

Asked how many times staff had complained about bullying in the last 12 months, NHS Lothian said there had been 40 cases.

This compares to 27 in NHS Lanarkshire, 26 in Ayrshire and Arran, 13 in Glasgow and seven in Forth Valley.

The Scottish Government stressed all health boards must have a "zero-tolerance" approach to the problem.

However, Theresa Fyffe, ­director of the Royal College of Nursing Scotland, said the figures raised questions about whether the robust policies and procedures in place to address bullying were being used.

She also expressed disappointment that some health boards, such as NHS Grampian and NHS Orkney, were unable to provide figures showing the number of bullying incidents investigated.

Ms Fyffe said that following meetings with the First Minister, Health Secretary and leaders of other political parties, it had been proposed a champion should be appointed in each board to address bullying and harassment and a report should be made available at board meetings to record progress.

She added: "So it's disappointing that two boards were unable to even report how many times staff complained about bullying over the last 12 months"

Rhoda Grant, wellbeing spokeswoman for Scottish Labour, obtained the figures by asking all health boards how many times staff had complained about bullying in the past 12 months. A total of 163 cases were reported in the responses they gave.

Ms Grant said it was vital that all complaints were treated in a sensitive and serious manner and were compressively addressed. She added: "We also have to ensure that this is a full record of the ­problem faced within our health service. We have to ensure that the right structures are in place."

An external report found an "undermining, intimidating, demeaning, threatening and hostile working environment" in NHS Lothian in 2012. It was ordered in the wake of revelations that waiting lists had been manipulated to hit targets.

In response to the new figures on bullying complaints, Alan Boyter, director of human resources and organisational development for NHS Lothian, said the health board was "committed to tackling bullying and harassment across the organisation".

He added: "NHS Lothian ... have worked hard to proactively encourage staff to use the range of confidential channels available in order to raise concerns, which may explain the number of complaints we have received in the last year."

Dr Peter Bennie, chairman of the BMA in Scotland, said: "It is essential we encourage NHS staff to share their concerns immediately and ensure that those who have the courage to come forward will be taken seriously, dealt with confidentially and have their concerns investigated quickly without risk of victimisation or repercussions."

A Scottish Government ­spokeswoman said: "The Scottish Government is clear that bullying is totally unacceptable and all health boards must have a zero-tolerance approach to any bullying and harassment. We have also created the National Confidential Alert Line for NHS Scotland staff to raise any concerns they have in confidence."