Image caption Dame Elish Angiolini says justifying the requirement for corroboration would be a "significant challenge" at the European Court of Human Rights

A former Lord Advocate has warned that Scotland's law of corroboration could be challenged at the European Court of Human Rights in Strasbourg.

Dame Elish Angiolini told BBC Radio Scotland the system needed to change to ensure more rape case convictions.

Corroboration requires two sources of evidence that back each other up, and this makes convictions difficult in serious sexual assault cases.

The Scottish government has already proposed abolishing the rule.

It has brought forward the Criminal Justice (Scotland) Bill which would drop the general requirement for corroboration in court cases.

It would also introduce safeguards such as increasing the number of jurors required for a majority guilty verdict.

'Two competing statements'

The move has been opposed by the legal profession, including judges.

The Law Society of Scotland has described corroboration as a "fundamental principle" of the justice system.

It has said removing it could simply result in a contest between two statements on oath and, as a result, bring increased risk of miscarriages of justice.

However, Ms Angiolini said she thought justifying the requirement for corroboration would be a "significant challenge" at the European Court of Human Rights.

She said a third of all rape cases in Scotland were marked "no proceedings in law" because of a lack of corroborative evidence.

"My own view is that it will not be long before a victim in a case, which is marked 'no proceedings', will take the Scottish system to the European Court at Strasbourg," she said.

"[And they will] say that because of this requirement, in sexual offending in particular, that they are unable to obtain effective criminal sanctions in Scotland."

She insisted that even if the law was to change prosecutors would continue to seek corroboration.

"Whether it requires to be a legal requirement is the issue," she said.