A 25-year-old mechanic and loner from a small Czech town, who tried to travel to Syria in January, was charged Tuesday with attempted terrorism, in what the authorities said was the first known case of a Czech citizen trying to join the Islamic State.

“This is the first time a Czech citizen has been charged with this crime,’’ said David Unger, a spokesman for the regional court in Plzen, in the western Czech Republic, which will rule on the next steps of the man’s detention Thursday.

The case has stirred anxieties that homegrown Islamic radicalism may have migrated to Eastern and Central Europe.

The regional prosecutor’s office in Plzen, which is handling the case, declined to provide further details. But Respekt, an influential Czech weekly that reported on the arrest this week, said the man — identified by the Czech media as Jan S. — had been arrested at an international airport in Turkey after the authorities there found him carrying a plane ticket to a Turkish town near the Syrian border.

The magazine reported that the man had told the police that he planned to enter Syria and join the Islamic State. After Turkish authorities sent him back to the Czech Republic, he was repeatedly questioned by police officers before being arrested two weeks ago.

Marian Brzybohaty, a terrorism expert from the Czech Police Academy, said it was not yet clear how the arrested man had become radicalized. Nevertheless, he said the case had punctured the notion that the Czech Republic was immune from homegrown radicalism.

“We don’t know whether he had psychological issues rather than having been radicalized,’’ Brzybohaty said.

New York Times