Frankfurt am Main (AFP) - A German neo-Nazi on trial over the murder of pro-refugee politician Walter Luebcke admitted Wednesday to the killing that has shocked the nation and highlighted the growing threat of right-wing extremism.

"I fired the shot," Stephan Ernst, 46, told the court of the killing in a statement read out by his defence.

Federal prosecutors have said Ernst was motivated by "racism and xenophobia" when he allegedly shot Luebcke in the head on June 1, 2019.

Luebcke's killing is believed to be Germany's first far-right political assassination since World War II.

Apologising to the victim's family, Ernst said he had carried out a "cowardly and cruel" act.

He insisted that he did not act alone but along with co-defendant Markus Hartmann, who stands accused of helping him train with firearms -- including the murder weapon.

"I know that what I and Hartmann did to you will always be inexcusable. What we did was wrong," he told the family in the statement.

"No one should die because he has another view," said Ernst, adding that he had been "misled by wrong ideas".

'Hatred of foreigners'

Luebcke belonged to Chancellor Angela Merkel's conservative CDU party and headed the Kassel regional council in the western state of Hesse.

He supported Merkel's 2015 decision to open the country's borders to refugees, with more than one million arriving since then, and spoke in favour of hosting asylum seekers in a local town.

Prosecutors say Ernst and his accomplice attended a speech by Luebcke in October 2015 when the politician defended helping refugees, adding that anyone who did not agree with those values was "free to leave the country".

The remark was widely shared online and turned Luebcke into a hate figure for the far right.

After the speech, Ernst "increasingly projected his hatred of foreigners" on to Luebcke, according to the indictment.

Angered by mass sexual assaults by migrants against women in Cologne on New Year's Eve 2015 and the 2016 terror attack in the French city of Nice, Ernst "began planning the murder in earnest" and started tracking Luebcke's movements, the indictment said.

Between 2016 and 2018, prosecutors say Ernst worked with Hartmann to improve his skill with firearms, and the two attended right-wing demonstrations together.

In the course of their investigations, prosecutors separately charged Ernst with attempted murder for allegedly stabbing an Iraqi asylum seeker in the back in 2016.

Long criminal history

Ernst has a long criminal history and was known to police as a neo-Nazi sympathiser.

He was convicted of an attempted bomb attack on an asylum home in 1993. In 2009, German media say he took part in clashes between neo-Nazis and union members at a demonstration.

But Ernst then slipped off the security services' radar, leading to criticism that the authorities were not taking the far-right threat seriously enough.

German law enforcers have been under fire for overlooking racist crimes after it emerged that a neo-Nazi terror cell, the National Socialist Underground, had killed 10 people, mostly immigrants, between 2000 and 2007.

The country has also been hit by a string of far-right attacks over the last year.

In October 2019, just months after Luebcke's death, Germany was rocked by a shooting at a synagogue in the eastern city of Halle that left two dead. The suspect later admitted to anti-Semitic and far-right motives.

In February this year, another gunman shot dead nine people of migrant origin in the central town of Hanau.

Interior Minister Horst Seehofer recently declared far-right extremism the "biggest security threat facing Germany".

He has promised tougher security measures, including a crackdown on online hate speech.