Munich - Two young men who beat up an elderly former school principal were given severe jail terms Tuesday, closing a case that triggered debate in Germany about violence by minorities.

Serkan A, aged 21, who is a Turkish national, was jailed for 12 years. Spyridon L, aged 18, who has Greek nationality, was jailed for eight and a half years. Both grew up in Germany. Politicians had demanded earlier they be expelled to their parents' homelands.

They were convicted of attempted murder in the Munich attack, which was filmed by closed-circuit TV security cameras on December 20, 2007, and aired for weeks on German television, arousing rage among many Germans during the Christmas season.

After the former teacher, 76, sternly reminded the two smokers that the underground mass-transit station was a non-smoking zone, they knocked him to the ground and kicked him in the head, nearly killing him.

The accused, who were 17 and 20 at the time, were convicted by a youth court in Munich. L is to serve his term in a youth prison. They admitted the attack and apologized to the victim in court.

He has largely recovered from a triple fracture to the skull and internal bleeding, but testified at the trial that he still had head pain. He told reporters he did not regard the apologies as sincere.

The assault in Bavaria was seized on by Roland Koch, premier of the neighbouring state of Hesse, who was running for re-election, to suggest that violence worsened if the courts were too reluctant to jail teen youths for minor violence.

Koch and other centre-right figures called for special youth jails, or boot camps, with a focus on arduous exercise and military- style discipline. Chancellor Angela Merkel voiced support for brief custodial sentences as a deterrent to juveniles.

Throughout January, the German news media highlighted cases of violence by minority youths amid calls for deportation of offenders, but the controversy has since calmed.

The issue did not save Koch, whose vote share declined in a state election. He now rules Hesse at the head of a minority government.

The trial was closely followed by the German media. Defence counsel said a conviction for assault would have been enough, and argued that sentences of about two years would have sufficed. (dpa)