Angus MacNeil was yesterday forced to issue a humiliating apology over an incident involving two teenage girls in his hotel bedroom. The 36-year-old Western Isles SNP MP admitted a lapse of judgment.

Angus MacNeil was yesterday forced to issue a humiliating apology over an incident involving two teenage girls in his hotel bedroom.

The 36-year-old Western Isles SNP MP admitted a "wrong and stupid" lapse of judgment over "some foolishness at a post-ceilidh party" with the pair in Shetland at a time when his wife was at home on Barra preparing to give birth to their child.

Although the three did not have sex two years ago, the revelations of what a Sunday newspaper dubbed a "drunken romp" are a serious blow to Mr MacNeil's campaign against the Prime Minister over allegations of cash for honours and an unwanted diversion from the SNP's attempt to wrest the Holyrood seat from Labour next month.

Mr MacNeil apologised yesterday for the "embarrassment and hurt" caused by his actions. Judie Morrison, from Stornoway and Catriona Watt, from Harris, told the Sunday Mail about the encounter in Shetland in July 2005 when they were aged 17 and 18.

The teenagers, now students at the Royal Scottish Academy of Music and Drama in Glasgow, were appearing in Shetland as musicians in Teine, an all-female Celtic group.

This year Ms Watt was voted BBC Radio Scotland Young Traditional Musician of the Year.

They said they had been on a pub crawl when they met the MP in a hotel. Ms Morrison said he bought them drinks before asking if they wanted to go to his room.

She said: "We got to his room and we all ended up in one bed. We were having a giggle and he was being very suggestive.

"He took off some of his clothes and I was sitting on the end of the bed and Catriona was lying beside him in the bed. I did heavy petting and I kissed him, we both did that with him."

Mr MacNeil said in a statement issued yesterday: "I bitterly regret that this incident occurred and I apologise to my family for causing them embarrassment and hurt.

"I also apologise to the young women involved and their families. I really should have known very much better. Yes, some foolishness took place at a post-ceilidh party, which was wrong and stupid.

"There is no allegation that anything further happened and I wish to make that absolutely clear. It was a lapse of judgment two years ago, for which I am sorry.

"I am really angry with myself for allowing a Labour-supporting newspaper the opportunity to divert attention from the substantial political issues which I have been pursuing. However, in the interests of everyone concerned, I have nothing further to say on this matter."

It was claimed by the online Westminster columnist Iain Dale that the MP has been facing a "dirty tricks" operation.

Three different forces were said to be investigating, with the Metropolitan Police sweeping the SNP office at Westminster for bugs. Claims that Mr MacNeil has been followed during visits to Glasgow have been reported to Strathclyde Police, while Northern Constabulary have been contacted about several phone calls to the MP's Barra home.

The story will no doubt cast a cloud over SNP leader Alex Salmond's campaigning visit to the Western Isles today and tomorrow - a visit in which it appears Mr MacNeil will play no part.