A Russian court on Friday sentenced a Ukrainian teenager to six years in prison for plotting a bombing in a Russian school.

Pavlo Gryb is one of many Ukrainians who have been put on trial in Russia in the past years for various crimes since Russia's annexation of the Crimean Peninsula from Ukraine in 2014.

Yet Gryb's case stands out, as the 19-year-old was kidnapped in summer 2017 in Belarus where he had traveled to meet a girl he met online. He later surfaced in a Russian prison.

Gryb claims he was having an online romance with the girl but says it turned out to be an officer from the Russian intelligence services who was messaging him on her behalf shortly before his trip.

Investigators claimed that Gryb was messaging the student online and was trying to get her to plant an improvised explosive device in her school in southern Russia. Gryb denies the charges.

The teenager has a grave liver condition that has deteriorated during his time in custody, and Ukrainian authorities have long argued for his immediate release, saying that Gryb may not survive the transportation and imprisonment in the high-security prison he is being sent to.

"Instead of urgent surgery that Pavlo needs because his life is in real danger, he has received this idiotic sentence of six years," Ukrainian Foreign Minister Pavlo Klimkin told The Associated Press in Kiev on Friday.

Klimkin said he would continue to raise Gryb's case with all his foreign counterparts.

"We have to save Pavlo, we have to help him," he said.