IN January 1941, Ursula Kuczynski, a Jewish German refugee, arrived in Oxford with her children on a British passport.

To her neighbours and the outside world she was a mother and housewife, but in reality she was a Soviet spy, codenamed Sonya, who spent the following decade relaying atomic secrets to the Russians.

Now her story has been turned into a documentary by filmmakers Oxford Digital Media and could be shown on TV channels around the world.

Sonya: The Spy who stole the Atom Bomb combines dramatic reconstruction with eyewitness accounts from her youngest son Peter Beurton and interviews with leading intelligence historians.

Filmmakers gained exclusive access to recently declassified archive files from MI5, as well as files from the KGB in Russia and German security services.

The idea for making the documentary came to Oxford Digital Media managing director James Tomalin from an article in Mail sister paper The Oxford Times, headlined Red Sonya - The spy who lived in Kidlington, in August 2010.

The 60-minute film was directed by James Tomalin, executive producer at Oxford Digital Media, and produced by Hannah Veale.

Father-of-two Mr Tomalin, who lives with wife Emma in Hook Norton, near Chipping Norton, said: "We found Sonya’s story irresistible as it has all of the elements of a classic spy tale.

"We found it hard to imagine that someone so seemingly ordinary could live such a secret life right here in Oxford.

"The more we learnt about Sonya, the more we realised there is still so much to discover and we hope this film will inspire more people to take an interest."

Mr Tomalin said the film has now been picked up by Drive TV for distribution and already sold to broadcasters in Germany, Denmark, France and Australia.

He added: "An intelligence historian took us through boxes of original documents and reports on her movements - new material is becoming available all the time.

"We also contacted her son, Peter Beurton, and together we visited the old family home in Berlin."

Mr Tomalin said Ursula Kuczynski came to Oxford during the Second World War when Blenheim Palace was being used as a base for MI5.

He added: "The Russians were aware of the development of atomic weapons and she would get secrets from Klaus Fuchs, who was at Harwell, and they would meet at Banbury railway station.

"She lived in Kidlington from the mid-1940s, and also lived in Great Rollright and in Glympton."

Mr Tomalin said after the spy began to be investigated she 'disappeared', before surfacing in East Germany.

After writing her memoirs she returned to Oxfordshire in the 1990s before she died in 2000.

Mr Tomalin added: "It's a fascinating story - we hope other broadcasters will take up the documentary soon."

A screening will take place from 6pm on Wednesday, March 15 at St Antony's College in Oxford.