A 14-year-old Austrian teen with ties to Islamic extremists has been convicted of planning to bomb a Vienna train station and has been sentenced to eight months behind bars.

The schoolboy, named only as Mertkan G, has also been found guilty of belonging to a “terrorist” organisation and given an additional suspended jail sentence of 16 months by a court in his hometown of Sankt-Poelten.

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According to the charge sheet, the teenager, who emigrated from Turkey in 2007, wanted to carry out the attack before travelling to join “holy war” in Syria alongside Islamic State.

Police had said at the time of his arrest in October 2014 that the boy made “concrete enquiries about buying ingredients” for a bomb and “planned to explode the devices in public places, such as the Vienna Westbahnhof,” a major train station.

His lawyer Rudolf Mayer had said that his client – who turns 15 in the coming days – had only been “playing with the idea” of making a bomb.

He has been in custody since January after breaking the terms of his parole.

Unconfirmed press reports said that ISIS had offered to pay him 25,000 euros ($A35,000) if he managed to carry out the attack.

In common with other European countries, Austria has seen a steady flow of people leaving or attempting to leave the country in order to join ISIS militants in Syria and Iraq.

According to the Austrian interior ministry, more than 200 have done so, including some women and minors. Around 70 have since returned, several of whom are in custody awaiting trial.