The case has been referred to the High Court in Edinburgh

During the trial the woman said she had repeatedly asked Mr Watt to leave her room and had begged him to stop.

Mr Watt argued that she was a willing partner.

Lord Abernethy agreed with a defence motion that Mr Watt had no case to answer.

In a controversial ruling, the judge said that to have sex with a woman without her consent was not rape, unless there was evidence of a degree of force or threat of force.

It was a ruling which drew fierce criticism from women's groups and some MSPs.

Appeal Court

After receiving a report on the trial from the Crown Office officials involved, the Lord Advocate Colin Boyd QC is to refer the ruling to the High Court of Justiciary sitting as an appeal court.

Three senior judges will consider the issues raised during the trial - in effect they are being asked to clarify what legally constitutes rape.

But whatever they decide will not affect Edward Watt's acquittal at the High Court in Aberdeen.

Mr Boyd's decision was announced to the Scottish Parliament on Wednesday by deputy justice minister Iain Gray, during a Members' Business debate about Lord Abernethy's ruling.

The High Court of Justiciary, sitting as an appeal court, will set a date for the matter to be considered by three High Court judges at the Appeal Court in Edinburgh.