PRAGUE (AP) — A Prague appeals court has increased a prison sentence to six years for a Czech man convicted of an attempt to join Islamic State group militants in Syria.

The regional court in the western city of Plzen sentenced Jan Silovsky to three years and three months in prison in February and ordered him to undergo psychiatric treatment.

The 22-year-old Silovsky pleaded guilty and expressed regret but appealed.

Prague's High Court upheld the ruling and increased the sentence at the prosecution's request. Tuesday's verdict is final.

Silovsky became the first Czech indicted for such a crime. He was arrested last year in Turkey at Istanbul's international airport and sent back to the Czech Republic by Turkish authorities.

During the trial, he said he converted to Islam about four years ago.