The director of one of Scottish theatre's biggest artistic triumphs, Black Watch, has left the National Theatre of Scotland.

John Tiffany, who directed the play by Gregory Burke, which has subsequently won a raft of awards and toured the world, has stepped down as associate director of the NTS to focus on his burgeoning directing commitments elsewhere.

A close colleague and friend of departing artistic director Vicky Featherstone, Mr Tiffany, originally from Huddersfield and educated at Glasgow University, won a prestigious Tony award for his direction of the musical Once earlier this year when it was staged on Broadway in New York. It is expected he will direct more work in the US in the future.

He will remain in touch with the NTS next year by directing two of its productions, the touring Black Watch and the new play, Let The Right One In, based on a novel by John Ajvide Lindquist, which will be staged at the Dundee Rep.

Prior to his appointment at the National Theatre of Scotland he was associate director at Paines Plough theatre company and before that was a multi-award winning literary director of the Traverse Theatre in Edinburgh.

For the NTS he also directed shows such as Elizabeth Gordon Quinn, Home Glasgow, The Bacchae and Peter Pan.

Black Watch was first performed during the Edinburgh Festival Fringe in 2006 at a former drill hall in Edinburgh and remains the landmark work of the NTS. It has now played to more than 200,000 people across three continents.

Mr Tiffany's departure – although it is likely he will return as a guest director in the future – will mean the new artistic director of the NTS, Laurie Sansom, will have the chance to appoint his own associate director.

Mr Sansom has already met and discussed future plans with a another key talent associated with the NTS, the playwright David Greig.

Mr Tiffany said: "Being associate director at the National Theatre of Scotland in its formative years has changed my life.

"From the first moments discussing possible ideas for our new programme, to Black Watch opening in South Korea, it has been a privilege and an honour to be part of the best theatre company in the world.

"This opportunity has taught me so much about theatre and I have grown as a person and as a director, learning from brilliant Scottish artists and audiences."

He added: "One of my most memorable experiences was spending six weeks in Thurso with Johnny McKnight, Steven Hoggett, Rob Drummond and the rest of the Hunter team to create a project with and for the community and pupils of Thurso High School. The project was called Transform, because it was about transforming communities – I was the one who left transformed."

Ms Featherstone said: "I am delighted John will be working with the National Theatre of Scotland in 2013, and hopefully beyond, to continue making brilliant theatre."