Emirati authorities are pushing ahead with plans to impose tighter government restrictions on the most secure BlackBerry service next week, according to the CEO of one of the Gulf nation's phone companies.

But Osman Sultan, chief executive of the telecommunications firm Du, told reporters today he doesn't expect the shift May 1 to cause problems for customers, who will still have access to email, Web browsing and messaging services.

His company and its rival Etisalat - both majority owned by the government - are required to implement the new policy, which would limit access to the Blackberry Enterprise Server to companies with 20 accounts or more. That system provides the most secure communication on the handheld devices and is used by many international companies and government agencies.

Other users would need to rely on a less-secure system known as the BlackBerry Internet Service that experts say could be easier for authorities to monitor.

"I don't see any reason for frustration for customers," Sultan said. "You can still access your corporate email via BIS. ... I don't see what really is the issue." The UAE's Telecommunications Regulatory Authority disclosed the change in policy earlier this month.

Six months ago, it backed down from a threat to impose a more sweeping ban on the most popular BlackBerry services amid concerns about security.

Shortly after details of the latest restrictions became public, the TRA issued a brief statement reassuring BlackBerry users that all services would continue for both individuals and business customers, prompting speculation it might roll back plans to limit the higher-security service.

It has not commented further on the matter since. It did not respond to a request for clarification today.

Sultan's comments suggest the restrictions are still moving ahead.

"The rule is still this rule," he said.

Research in Motion Ltd, the Canadian company that makes BlackBerrys, has said it is in contact with the regulator and understands that the rules could apply to other smartphone makers but aim to avoid affecting "legitimate enterprise customers."

The UAE's smartphone policies have been closely watched since last summer when it threatened to shut off BlackBerry data services partly because of security concerns. It backed off the plan in October.