A 14-year-old Austrian schoolboy with alleged ties to Islamist extremists and accused of intending to bomb a Vienna train station went on trial Tuesday facing up to five years in prison.

The defendant, named only as Mertkan G., was arrested in October 2014 and allegedly had contact with supporters of the Islamic State (ISIS) jihadist group and Al-Qaida, the court in his hometown of Sankt-Poelten said.

"In addition he is suspected of obtaining instructions on how to make an explosive device from an Al-Qaida website... in order to carry out an attack in Vienna," the court 70 kilometers (45 miles) west of the Austrian capital said.

According to the charge sheet, the teenager, who emigrated from Turkey in 2007, wanted to carry out the attack before traveling to join "holy war" in Syria and was in contact with ISIS recruiters in Vienna.

Police had said at the time of the arrest that the boy made "concrete inquiries 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 told AFP that his client — who turns 15 next week — 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 jihadists had offered to pay him 25,000 euros ($27,250) 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.