A member of the ruling family in the northern United Arab Emirates was under palace guard Wednesday in an apparent crackdown on Islamist groups and others viewed as challenging the UAE's political system, a rights group said.

The London-based Emirates Center for Human Rights said Sheik Sultan al-Qasimi, a cousin of the ruler of the emirate Ras al-Khaimah, was being held after being detained by armed men late last week.

The UAE bans formation of political parties and has moved decisively to prevent the popular uprisings that swept the Mideast last year from reaching its turf, arresting pro-reform activists and charging them with serious crimes.

Officials in the UAE have made no official comment about the latest detention.

Sheik Sultan is chairman of an Islamist group and has been under pressure for calling for democratic reforms in the Western-allied UAE, which is controlled by the ruling families in each of the seven semi-autonomous emirates.

Six pro-reform activists — some of them members of the same Islamist group, known as al-Islah — are also being held by UAE officials after being stripped of their citizenship for criticizing the country's rulers.

It's unclear, however, whether Sheik Sultan will be formally charged, because he holds a senior position in the ruling family in Ras al-Khaimah, the emirate at the northern tip of the UAE.

Sheik Sultan posted an opinion piece online in April criticizing a federal government crackdown on the Islamist activists who were stripped of their citizenship late last year. The government cited national security concerns in moving against the men, but the activists say they were targeted for calling for political reform.

In the opinion piece, Sheik Sultan linked online activism among Emirati youth to the mass protests in Cairo's Tahrir Square, which led to the resignation of Egypt's longtime ruler, Hosni Mubarak. It suggested, at least indirectly, that ripples from the Arab Spring were spreading the Gulf federation, whose leaders have been spared the street protests seen elsewhere in the region.

In a statement posted late last week, the al-Islah group condemned al-Sultan's detention. Efforts to contact the Ras al-Khaimah ruler's palace were unsuccessful.

UAE authorities have consistently moved aggressively to head off any signs of dissent.

Last year, five political activists, including a prominent blogger and an economics professor who has frequently lectured at Abu Dhabi's branch of the Sorbonne university, were convicted of anti-state crimes after signing an online petition calling for a greater public voice in the country's affairs.

They were freed on a presidential order, but the charges against them have not been officially dropped.

Dubai's police chief, Lt. Gen. Dahi Khalfan Tamim, has repeatedly raised alarms about the widening influence of Islamist groups, including factions inspired by Egypt's powerful Muslim Brotherhood.

Earlier this month, the UAE temporarily detained members of a U.S.-funded democracy group as they tried to leave the country after their Dubai office was ordered closed.

At the time, UAE officials said the National Democratic Institute, or NDI, was closed over licensing issues. Branches of a German pro-democracy group, the Konrad Adenauer Foundation, were also closed along with the Abu Dhabi office of the polling organization Gallup.


Associated Press writer Adam Schreck contributed to this report.