By Katharine Jackson

WASHINGTON (Reuters) - The number of hate groups operating in the United States rose 7 percent to an all-time high last year, the Southern Poverty Law Center said on Wednesday, attributing the increase largely to anti-immigrant rhetoric from President Donald Trump.

The SPLC, which has tracked hate groups since 1971, found there were 1,020 operating in the United States in 2018, breaking the 1,018 record set in 2011. It marked the fourth consecutive year of growth.

The group blamed Trump, whose administration has focused on reducing illegal and legal immigration into the United States.

"The words and imagery coming out of the Trump administration and from Trump himself are heightening these fears," Heidi Beirich, director of the SPLC's Intelligence Project, told reporters on a conference call. "These images of foreign scary invaders threatening diseases, massive refugee caravans coming from the south. This is fear-mongering."

The White House has repeatedly rejected charges of bias leveled at Trump, often citing the effects that a strong economy have had on minority communities. It did not respond to a request for comment on the report on Wednesday.

The SPLC defines hate groups as organizations with beliefs or practices that demonize a class of people. The number of groups has risen 30 percent since 2015 when Trump declared his presidential candidacy.

The last surge in new hate groups came in the early years of Barack Obama's presidency, a reaction to the first black U.S. president, the group said. The number rose 9 percent during the first three years of Obama's administration to reach the prior record then dropped until 2015.

The group also cited online incitement for the rise. Despite efforts to regulate content on mainstream websites including Facebook, the internet still provides the most fertile ground for hate groups to recruit new members, SPLC said.

The non-profit said the growth of hate groups appeared to spur some who share their ideologies to take violent action. It cited Robert Bowers, who is accused of killing 11 worshippers at a Pittsburgh synagogue in October while shouting "All Jews must die."

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As part of SPLC's count of hate groups, black nationalist groups rose 13 percent to 264 in 2018, an increase SPLC attributed to a backlash against Trump's policies.

Some of the SPLC's targets have criticized the Montgomery, Alabama-based organization's findings, saying it mislabeled legitimate organizations.

Earlier this month the founder of the Proud Boys, a self-described men-only club of "Western chauvinists," sued the center for defamation. He contended the Proud Boys oppose racism, while the SPLC said it stood by its research.

(Reporting by Katharine Jackson; Editing by Scott Malone, Tom Brown and Cynthia Osterman)