Image caption Harry Ferrier in The Radicalisation Of Bradley Manning. Photo: Farrows Creative/National Theatre Wales

A play about Bradley Manning, the American soldier convicted of releasing US state secrets to Wikileaks, has won the new theatre category of one of Britain's oldest literary awards.

The Radicalisation of Bradley Manning by Tim Price is the first play to win the James Tait Black prize for drama.

The existing book prizes for fiction and biography have been awarded by the University of Edinburgh since 1919.

More than 180 plays were considered for the new drama prize, worth £10,000.

Manning was arrested in May 2010 and locked up for three years before his trial, which ended last week when he was convicted of most of the charges against him.

He faces a lifetime in prison when he is sentenced for leaking the documents to anti-secrecy organisation Wikileaks, which he claimed he did to spark a debate on US foreign policy.

The leak is considered the largest ever of secret US government files.

The play was originally performed in schools across Wales in April 2012, and opened at Tasker Milward School, Haverfordwest, which Manning attended in his teens.

Image caption The play was originally performed in Wales, where Manning spent his teenage years

Tim Price's script charts the story of Manning's life, from his teenage years growing up in Wales to his incarceration in the US.

The James Tait Black judging panel said that the contemporary nature of the play, its important subject matter, its unique theatrical voice and inventive use of structure made Price's work a clear winner.

Neil Murray, executive producer at The National Theatre of Scotland, who had a role in judging the awards, said: "His play is emotionally resonant on many levels, challenges thinking and teaches us things we did not know with a truly unique voice - exactly what this prize sets out to recognise."

Price said: "The play is being performed by National Theatre Wales as part of the Edinburgh Festival Fringe this month, so we hope that this fantastic accolade will encourage more people to see the play."

The shortlist for the award also included: The Hundred Flowers Project by Christopher Chen; Foxfinder by Dawn King; In Water I'm Weightless by Kaite O'Reilly; The Effect by Lucy Prebble.

The drama prize was judged by students and academics from the University of Edinburgh, as well as representatives from the National Theatre of Scotland.

The existing James Tait Black Prizes for fiction and non-fiction will be announced at a ceremony at the Edinburgh International Book Festival on 24 August.