Florida is declaring the Council on American-Islamic Relations (Cair) – a US civil rights and liberties group – a foreign terrorist organization, the Republican governor, Ron DeSantis, announced on Monday.

The move closely follows a similar order issued in November by Texas’s governor, Greg Abbott, DeSantis’s fellow Republican, even though only the federal government can designate terrorist organizations.

Cair and its supporters are among those who have dismissed the orders from DeSantis and Abbott as Islamophobia.

In a statement, the national and Florida Cair chapters described DeSantis’s order as a “stunt” and accused him of signing a “defamatory and unconstitutional order baselessly smearing” them. The groups vowed to sue Florida as it has Texas, where Abbott has directed law enforcement officials to investigate whether a group in Dallas is operating courts under sharia law.

“Governor DeSantis knows full well that Cair-Florida is an American civil rights organization that has spent decades advancing free speech, religious freedom and justice for all,” including for the people of Palestine, the groups said in a statement.

DeSantis said the executive order naming Cair, one of the nation’s largest Muslim advocacy groups, was “effective immediately”. His order also targets the Muslim Brotherhood, a transnational Islamist group founded in 1928.

Neither the Muslim Brotherhood nor Cair are on the US government’s list of designated FTO groups.

Nonetheless, “Florida agencies are hereby directed to undertake all lawful measures to prevent unlawful activities by these organizations, including denying privileges or resources to anyone providing material support,” DeSantis said in a statement on X.

The order said Cair was “founded by persons connected to the Muslim Brotherhood,” which it connects to Hamas and the 7 October 2023 attack on Israel. Cair denies ties to Hamas and the Muslim Brotherhood.

Cair’s Florida and national chapters said DeSantis through his order had prioritized “serving the Israeli government over serving the people of Florida” – and of diverting “millions in Florida taxpayer dollars to the Israeli government’s bonds”.

DeSantis and Abbott, it added, want “to smear and silence Americans, especially American Muslims”, who criticize the US’s support for Israel’s war in Gaza.

In a separate statement on X, DeSantis said that members of the Florida legislature “are crafting legislation to stop the creep of sharia law, and I hope that they codify these protections for Floridians against Cair and the Muslim Brotherhood in their legislation”.

Abbott’s order in Texas prohibited Cair and the Muslim Brotherhood from acquiring property in the state and authorizing legal action to shut down affiliated entities.

Cair sent a letter to Abbott in November saying it “has spent 30 years vocally speaking up against all forms of bigotry, including anti-Black racism, Islamophobia, anti-Palestinian racism and antisemitism, as well as all forms of unjust violence, including hate crimes, ethnic cleansing, genocide and terrorism”.