Plot to bomb white supremacists in California as revenge for Christchurch attacks thwarted

American authorities have thwarted an alleged plot by an army veteran to bomb a white supremacist rally as revenge for the Christchurch terror attacks.

On Friday (local time), 26-year-old Mark Domingo, a convert to Islam, was arrested while in the final stages of planning to plant a bomb at a white supremacist rally on Sunday at California's Long Beach.

He was charged with providing material support to terrorists.

The Associated Press reports that court documents show he had discussed attacks against Jewish people, churches and police officers. If he survived the bombing at Long Beach, he also allegedly had plans to attack other centres.

Domingo had allegedly planned, since March, to use a weapon of mass destruction to committ mass murder as revenge for the Christchurch mosque attacks.

After the shooting, he wrote on social media that there needed to be retribution.

Domingo's plans were discovered after trying to purchase explosive material online.

According to documents, he purchased three-inch nails as materials for the bomb because "they would be long enough to penetrate the human body and puncture internal organs".

He organised for them to be made into a live bomb but, after receiving the device, found it didn't work, reports CBS News.

The person he confided with to find a bombmaker, and later received the purposefully faulty device from, turned out to be an undercover FBI agent, who was part of a taskforce that later arrested him.

"This investigation successfully disrupted a very real threat posed by a trained combat soldier who repeatedly stated he wanted to cause the maximum number of casualties," said United States attorney for the Central District of California Nick Hanna.

Domingo will make his first court appearance on Tuesday (NZ Time).