Dubai, United Arab Emirates ? The United Arab Emirates outlined plans Sunday to block BlackBerry e-mail, messaging and Web browsing services in a crackdown that could jeopardize efforts to establish the country as an international business hub.

The government cited a potential security threat because encrypted data sent on the devices is moved abroad, where it cannot be monitored for illegal activity.

But the decision — quickly followed by a similar move in Saudi Arabia — raises questions about whether the conservative Gulf nations are trying to further control content they deem politically or morally objectionable.

BlackBerry phones have a strong following in the region, not only among foreign professionals in commercial centers such as Dubai and Abu Dhabi, but also among youths who see their relatively secure communication channels as a way to avoid unwanted government attention.

“The authorities have used a variety of arguments, like it can be used by terrorists” to justify the crackdown, said Christopher Davidson, a professor at the University of Durham in Britain, who has written extensively about the region. “Yes that’s true, but it can also be used by civil society campaigners and activists.”

The UAE’s decision will prevent hundreds of thousands of BlackBerry users from accessing e-mail and the Web on their handsets starting in October. It’s unclear whether the ban will extend to foreign visitors with roaming services, including the roughly 100,000 passengers who pass through the region’s busiest airport in Dubai each day.

The ban risks further damaging the UAE’s reputation as a relatively easy place to do business.

Dubai, one of seven hereditary sheikdoms in the federation, in particular has sought to turn itself into a global finance, trade and tourism hub.

But its reputation has been tarnished by a credit crisis that has left the emirate more than $100 billion in debt.

Residents say the BlackBerry crackdown will only do more harm, making foreign businesses think twice before setting up shop in the country.

“They’ll think now they’ve banned the BlackBerry, maybe next time it’ll be the Internet,” said Shakir Mahmood, a Dubai-based debt collector and BlackBerry user originally from Iraq.