US ARMY private Ethan Melzer has pleaded not guilty to terrorism offences, as he stands accused of planning a massacre of his unit by sending sensitive information to a neonazi group.

Prosecutors say the 22-year-old confessed to plotting a deadly attack during a voluntary interview with military investigators and the FBI on May 30.

According to court documents, Mr Melzer, who joined the army in 2018, planned an ambush on his unit in service of “a diabolical cocktail of ideologies laced with hate and violence.”

He is accused of using encrypted messaging apps such as Telegram to send details of the location and movements of his unit to white supremacist groups the Order of Nine Angles (O9A) and the RapeWaffen Division.

Prosecutors said that Mr Melzer joined O9A in 2019, and they described the group as espousing “neofascist, neonazi and anti-semitic beliefs.”

Files were seized by the FBI from an Apple iCloud account, according to court records.

When the charges were brought in June, the acting US attorney for the southern district of New York, Audrey Strauss, said: ”As alleged, Ethan Melzer, a private in the US army, was the enemy within.”

“Melzer allegedly provided this potentially deadly information intending that it be conveyed to jihadist terrorists. As alleged, Melzer was motivated by racism and hatred as he attempted to carry out this ultimate act of betrayal.”

In February, a survey of serving US armed forces personnel conducted by the Military Times found that “more than one-third of all active-duty troops and more than half of minority service members say they have personally witnessed examples of white nationalism or ideological-driven racism.”

The overall total, at a rate of 36 per cent, was a steep rise from the year before, when 22 per cent had reported witnessing such incidents.

Southern Poverty Law Centre spokeswoman Cassie Miller had not been surprised by the findings.

“Historically, this has been a problem for the military,” she said.

“We’ve been pushing the Defence Department to take this issue more seriously since 1986.

“There are certain parts of the white power movement that value military experience and are often recruiting there.”

Mr Melzer faces six charges, including conspiring to murder US nationals and conspiring to murder US military personnel — each of which carries a maximum life sentence — and providing material support to terrorists.