The Central Criminal Court of England and Wales in London, UK. Photo: Ben Sutherland / Wikimedia Commons.

A 16-year-old from Cornwall who led a neo-Nazi group has become the youngest person in the United Kingdom ever convicted of terrorism, the BBC reported Monday.

He spoke in online forums of “gassing” Jews and hanging gay people, the outlet reported, and admitted in court to 12 offenses of possessing and disseminating terrorist materials. He will face a sentencing hearing on Monday.

The unidentified teenager downloaded bomb-making instructions at 13, and joined the online forum Fascist Forge, a white supremacist group which the Anti-Defamation League (ADL) says “serves as a breeding ground for radicalization and offers a stringent indoctrination process.”

He later communicated with the Estonian founder of another neo-Nazi group, the Feuerkrieg Division, and started a chapter in the UK which pledged to pursue a “white jihad.”

The larger group “holds some of the white supremacist movement’s most extreme views,” according to the ADL, embracing violent action in pursuit of a whites-only ethno-state.

In court, prosecutor Naomi Parsons told the BBC, “The age is the alarming factor and his conduct betrays a maturity beyond his chronological age.”

In his defense, the teenager’s attorney told of a difficult childhood and claimed that the boy’s online activities were attention-seeking.