Tommy Robinson has branded 28-year-old Christchurch shooting suspect Brenton Tarrant a "monster".
When asked about the killings the activist told journalists he had always "called out" extremism.
"I don't follow the same book as this white supremacist," he said.
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"For 10 years I have called out white supremacy, the same as I've called out Islamic extremism. Any supremacy I've called out.
Mr Robinson reacted angrily when asked about the mass shootings.
Brenton Tarrant is charged with murder after the attack
"When there's an Islamic terrorist attack, do you go stand outside every mosque and ask the imam that follows the same book as the terrorist?" he asked.
"This monster wrote a manifesto.
"In that manifesto, is my name in it? Does he mention me?
"No he doesn't.
"He specifically tells you why he done it, but yet here you are as the mainstream media attempting to somehow associate me with a coward on the other end of the planet.
"How can you do that?"
Mr Robinson continued: "So when there's an Islamic terrorist attack, do you go stand outside every mosque and ask the imam that follows the same book as the terrorist?
"I don't follow the same book as this white supremacist.