DUBAI, United Arab Emirates — The United Arab Emirates said Thursday it is taking the rare step of revoking the citizenship of six men because of concerns they pose a threat to national security.

The unexpected order was issued by President Sheik Khalifa bin Zayed Al Nahyan earlier this month, according to an announcement by state news agency WAM.

The men's names are among those of seven people listed as having signed a statement posted online this week alleging their citizenship had been unjustly revoked because they had called for political reforms.

That statement identified them as members of an Islamist organization known as the Reform and Social Guidance Association. It urged the UAE's leaders to "stop all oppressive measures against advocates of reform in the country."

The state news agency quoted an unnamed source at the General Administration for Naturalization, Residency and Ports Affairs who said the six men had acted to threaten "the national security of the UAE through their connection with suspicious regional and international organizations and personalities."

Some of the men were associated with groups that have been linked with terrorist financing, the state news agency quoted the official as saying. They were granted Emirati citizenship between 1976 and 1986, according to the report.

It didn't provide details or say where the men originally came from.

A person familiar with the case told The Associated Press that four of the men were of Iranian origin and two came from Yemen. He said the men's Emirati citizenship status was revoked "once it became clear that the rules under which they were granted (citizenship) were being violated."

The person spoke on condition of anonymity because he was not authorized to discuss the matter publicly.

Officials at the naturalization and residency office couldn't immediately be reached for comment.

The seven-state UAE federation is a close ally of the United States. It has not seen the widespread anti-government protests that have rocked much of the Arab world this year, though officials have taken steps to tamp down indications of dissent.

Five political activists, including a prominent blogger and an economics professor, were convicted late last month on anti-state charges that included insulting the UAE's top leadership, endangering national security and inciting people to protest. They were pardoned by the federation's president a day after their sentences of two to three years in jail were handed down.