Suspect in Nazi bomb plot, linked to Christchurch killings, was kicked out of US Army

In this 2012 photo, US Army private Mark Domingo, left, takes an Afghan man's fingerprints in the village of Dande Fariqan, in Afghanistan's Khowst Province. Photo / AP

An Army veteran who converted to Islam and is accused of plotting terrorist attacks in California in retaliation for the Christchurch mosque killings was demoted and discharged from the military for a serious offence.

Mark Domingo violated the Uniform Code of Military Justice and was kicked out of the service before completing his enlistment contract, according to a US official.

Officials would not provide details on his offence.

Domingo, 26, was arrested at the weekend as he planned to plant bombs before a scheduled white supremacist rally in Long Beach, authorities say.

He was charged with providing material support to terrorists and held without bail.

Domingo, a former combat infantryman, had recently become Muslim and discussed several plots over the past two months to kill scores of people in Southern California in revenge for last month's attacks on the two mosques that left 50 people dead, federal prosecutors said.

The terror plot was foiled by the FBI and police using an undercover officer and informant, who Domingo thought were his accomplices.

Military records show Domingo served about 16 months in the Army, including a four-month stint in Afghanistan in fall 2012. He left with a rank of private, the lowest possible grade.

An Army photo of Domingo in Afghanistan in November 2012 identified him as private first class, which is two steps above his discharge ranking.

Domingo was given a general discharge, which is an administrative action a step below an honorable discharge, the official said.

- AP