Kenny Richey is facing execution

Richey was sentenced to death 17 years ago after being convicted of arson and the aggravated murder of a two-year-old girl in Ohio.

But campaign groups and politicians have contested the safety of the conviction.

Richey, from Edinburgh, is awaiting the outcome of his final stages of appeal.

The MPs and MSPs have submitted an Amicus Curiae Brief to the Circuit Federal Court of Appeal.

We are now running out of time to secure justice for Kenny Richey Alistair Carmichael MP

It comes from a Latin term meaning "friend of the court".

Human rights charities Reprieve and Amnesty International have supported the submission.

It also has the backing of the Law Society of Scotland, the Law Society of England & Wales and the Bar Human Rights Committee.

The campaign to release Richey has been led by Orkney and Shetland MP Alistair Carmichael.

Appeal decision

Mr Carmichael said: "I am delighted that so many of my parliamentary colleagues have signed the Amicus Brief in support of Kenny.

"He has now been on death row for over 17 years, despite very real doubts about the safety of this conviction.

"We are now running out of time to secure justice for Kenny Richey.

"It is vital that, as the legal avenues available to Kenny come to an end, the UK Government makes every possible effort to prevent his execution."

He added that Richey's supporters can now only wait for a decision, which could come any day.

Should the appeal fail, Richey's final chance would be an appeal in the US Supreme Court before an execution date would be set.