SCOTLAND is in breach of human rights law and could be taken to court over "extraordinary rendition" flights, according to a Glasgow law expert who has written to the lord advocate demanding urgent action be taken over them.

Dr William Henderson, lecturer in human rights and European law at Glasgow Caledonian University, has sent a letter to Elish Angiolini QC asking for new guidance to be given to chief constables so they can investigate claims of rendition.

Dr Henderson attended a meeting with justice secretary Kenny MacAskill in August, along with representatives of Amnesty International Scotland and human rights groups Reprieve and Liberty, to discuss Scotland's role in rendition flights. At that time MacAskill condemned the flights, but since then the government has not made any further statement.

Dr Henderson's letter states: "The Scottish ministers have been placed at risk to litigation under the European Convention of Human Rights through a lack of any independent or effective investigation into what are exceptionally serious allegations."

Dr Henderson says that over the past two years or so there have been many reports noting Scottish airports being used in the extraordinary rendition process. He added: "We would refer you to Below The Radar by Amnesty International and also Alleged Secret Detentions, etc, by the Council of Europe."

He told the Sunday Herald: "If anyone has been abducted and taken through a Scottish airport in the past few years, and the law enforcement agencies have not acted upon information given, that would fall foul of the convention."

Dr Henderson said that by not putting into practice guidance and policies to stop rendition flights from happening, ministers were breaching human rights law. "The point I want to make is if it does happen again, the police are guided by the prosecution and the lord advocate to allow them to intervene."

Rendition flights fall under justice and aviation. Justice is a devolved matter, but aviation is reserved to Westminster. This has led to confusion over whether Scotland has powers to investigate or legislate.

Dr Henderson said: "Doing something about rendition flights is within Kenny MacAskill's reach. In the Criminal Justice Act it says public officials, regardless of their nationality, if they have been involved in committing the crime of torture, should be arrested, and they have an obligation to do so."

Clara Gutteridge is an investigator for Reprieve, a human rights organisation run by lawyer Clive Stafford Smith, who specialises in political and death penalty cases and whose clients include victims of rendition. She said there was a "distinct possibility" they would look at calling for a judicial review of any government, including Scotland's, that refused to "recognise its obligations of a proper investigation of strong allegations they have been involved in rendition."

She added: "To say that human rights is reserved to Westminster is effectively to say that Scotland isn't in charge of its own legal system, and I don't see how you can say that."

John Watson, director of Amnesty International Scotland, warned it might be impossible to find out what happened on these flights. "We know some of the aircraft implicated in these rendition flights are still flying. One of them was spotted landing at Glasgow airport in August, so we still get sightings but we don't know what they are doing. That's always been our problem because we can't stop them and check."

Watson said he would like practical measures to be put in place, such as allowing police or customs to check what and who is aboard. Amnesty has campaigned for Scottish airports to follow the example of Derry airport, which has signed a protocol to prevent future rendition flights landing there.

"Everyone has said they are against torture, but I think that by not taking action you create the circumstances in which this activity can carry on," he said. "We have an obligation to make sure it doesn't happen again."

The Irish Human Rights Commission (IHRC) last month announced it would investigate Ireland's role in rendition flights, a precedent that Scotland's forthcoming Human Rights Commission could follow. However, it would seem the Scottish Commission for Human Rights (SCHR), which will be launched early next year under the umbrella of the new Equality and Human Rights Commission (EHRC), has yet to clarify its remit. An EHRC spokeswoman said: "Extraordinary rendition is a complex issue, with some aspects possibly lying with Westminster and others with Holyrood."

The Crown Office confirmed it had received Dr Henderson's letter and would reply "in due course".