Islamic extremists and white supremacists are using race-hate massacres around the world for recruitment and propaganda according to terrorism analysts, adding to fears that violence by radicals in both groups is becoming mutually reinforcing.

Rita Katz, the director of the Washington DC-based online security firm SITE Intelligence said that after far-right terrorist attacks like the one in Texas this week, supporters flood websites like 8chan and Gab with celebratory content, including posters of the attacker, quotes from their manifestos and calls for more violence.

She said following the El Paso shooting, the far-right have called the alleged terrorist, Patrick Crusius, a "saint," disseminating posters of him and calling for "white jihad".

"Others have even used Crusius’ attack as an opportunity to advise on other types of attack methods," Ms Katz said.