Scotland's second largest health board has apologised after long A&E waiting times went under-reported.

In November last year, a whistleblower raised concerns that breaches of the four-hour emergency access standard were going unrecorded at NHS Lothian.

Health secretary Shona Robison ordered an independent investigation into the claims, relating to St John's Hospital in West Lothian, to take place.

The report from the Academy of Medical Royal Colleges also raised concerns and said "urgent action" was needed to tackle bullying and harassment at NHS Lothian.

Professor Derek Bell's report did not find evidence of deliberate attempts to falsify figures but said there was a "fine line between falsification and confusion," with staff under pressure to meet the four-hour target.

NHS Lothian's chief executive Jim Crombie said he accepted the report's recommendations.

He said: "We have recognised from the outset that mistakes were made and accept the findings of this review. It's clear not all was as it should have been.

"Staff have also come under intense pressure and for these failings I'm really sorry.

"Since the publication of our own review last November we have already taken a number of steps to rectify the reporting errors including significant staff training to ensure correct recording of 4 Hour breaches.

"We are confident the measures we have already put in place have removed any ambiguity over the correct procedures."

He continued: "However, we also share the Scottish Academy's concern about bullying behaviour as reported by staff at many levels during the review, while recognising that there was no evidence of bullying and harassment at board level.

"In the face of intense and sustained pressure working relationships can sometimes be fraught and plainly we have not been doing enough to support our front line staff.

"We are working to identify practical ways to reduce pressure right across the system and undertaking a programme to develop our leaders.

"As part of that work we will, through all mechanisms, ensure that it is absolutely clear that NHS Lothian does not tolerate bullying behaviour."