The move came as child killer Karl Tonner sought to exploit a legal loophole which led to the release of Noel Ruddle.

BBC Scotland's Home Affairs Correspondent Reeval Alderson outlines what will happen next

Ruddle shot a neighbour dead in 1991 and was sent to Carstairs without limit of time, but earlier this month he convinced a sheriff he could no longer be treated there because his condition had changed.

Tonner, who has changed his name to Karl Anderson, began moves to win his freedom on similar grounds at Lanark Sheriff Court on Friday.

Now the Scottish Executive, which has faced severe criticism over its handling of the Ruddle affair, has announced proposals aimed at stopping any further releases.

Deputy First Minister Jim Wallace: "We acted as quickly as possible"

Justice Minister Jim Wallace said courts would be asked to take public safety into account when considering applications for release.

The bill, which will amend existing legislation, will go before the Scottish Parliament next week and also includes:

• A right of appeal for both parties.

• A power to detain patients pending the outcome of an appeal by the First Minister.

• A stipulation that the definition of mental disorder includes personality disorder.

The bill would mean that all appeals heard after it is introduced - that is likely to be next Wednesday - will be covered by the legislation.

The Scottish Executive has confirmed this would mean Karl Tonner's case, and that of Brian Docherty who is planning a similar action, would be affected by what would be a rare piece of retrospective legislation.

Mr Wallace said he had discussed the proposals with Scottish National Party justice spokeswoman Roseanna Cunningham and Scottish Tory leader David McLetchie.

Noel Ruddle: Sparked legal move

He said: "The key issue raised by the Ruddle case was where a sheriff has no alternative but to release a mentally ill patient if he is untreatable.

"Our legislation will place a requirement on the courts to take public safety into account when considering an application for release.

"The sheriff in Lanark was unable to do this in the case of Noel Ruddle. That is the loophole we are closing."

At Lanark Sheriff Court on Friday, lawyer Yvonne McKenna, who also represented Ruddle, made an application for Tonner's release.

Tonner killed a 12-year-old Dundee girl in 1968 and was sent to Carstairs without limit of time. He was not present in court for the short hearing.

The 51-year-old is seeking to use the same clause in the Mental Health Scotland Act 1984 as that employed in Ruddle's case.

Hearing adjourned

Miss McKenna asked for an adjournment and Sheriff Douglas Allan, who heard Ruddle's case, agreed to a hearing on 7 and 8 of October.

At the time of the killing, Tonner admitted culpable homicide, on the grounds of diminished responsibility.

He had stripped and strangled Helen Phin with a length of rope in a workhouse close.

Justice committee convener, Roseanna Cunningham, says the new legislation needs to watertight

Mr Wallace faced the brunt of the criticism over the Scottish Executive's handling of the Ruddle affair and there have been demands from the Scottish National Party for an independent inquiry.

The convener of the parliament's justice committee Roseanna Cunningham said: "We are only at this stage because of the Ruddle case and the fact that opposition put pressure on the Executive.

"The primary issue here is that of public safety. The second important issue is that we satisfy the European Convention on Human Rights."

Some reports suggest a further four killers in Carstairs are preparing to launch similar legal actions. One of them is 26-year-old Brian Docherty.