Republican Texas Gov. Greg Abbott on Tuesday declared one of the largest Muslim civil rights and advocacy groups in the U.S. a “foreign terrorist organization” under a proclamation that he said allows the state to try shutting them down.

He also designated the Council on American-Islamic Relations “a transnational criminal organization” and said it would not be allowed to buy land in the state. The proclamation also included the Muslim Brotherhood.

Neither the CAIR nor the Muslim Brotherhood are designated as foreign terrorist organizations by the U.S. government.

CAIR told Abbott in a letter that his announcement had no basis “in law or fact.” The group accused his office of stoking “anti-Muslim hysteria.”

“You do not have the authority to unilaterally declare any Americans or American institutions terrorist groups, nor is there any basis to level this smear against our organization,” wrote Robert S. McCaw, CAIR’s government affairs director.

Months ago, Texas Republicans moved aggressively to try to stop a Muslim-centered planned community around one of the state’s largest mosques near Dallas. Abbott and other GOP state officials launched investigations into the development tied to the East Plano Islamic Center, saying the group is trying to create a Muslim-exclusive community that would impose Islamic law.

EPIC City representatives called the attacks about Islamic law and other assertions misleading, dangerous and without merit. Earlier this year, the Justice Department closed a federal civil rights investigation into the planned community without filing any charges or lawsuits.

In his proclamation, Abbott cited a law he signed this year that he said prohibits “foreign adversaries” from purchasing or acquiring land. The Republican author of that bill praised the governor’s declaration.

“Today proves exactly why that law was needed,” Republican state Rep. Cole Hefner posted on X.

The Muslim Brotherhood was established in Egypt nearly a century ago and has branches across the world. Its leaders say it renounced violence decades ago and seeks to set up Islamic rule through elections and other peaceful means. Critics, including autocratic governments across the Mideast region, view it as a threat.