Human Rights Watch accused the United Arab Emirates of cracking down on freedom of expression, during a news conference on Wednesday which was disrupted by men who claimed to be UAE officials and demanded the rights group end its presentation.

The UAE, which includes the emirates of Dubai and Abu Dhabi, has avoided the kind of pro-democracy demonstrations that have rocked Tunisia, Egypt, Libya, Yemen, Bahrain and Syria, partly thanks to its cradle-to-grave welfare system.

But it has tolerated little dissent during the regional upheaval, trying and sentencing at least five pro-reform activists and stripping the citizenship of another seven last year on charges that they represent a threat to state security.

It also disbanded the elected boards of two of the UAE's most prominent civil society groups, Human Rights Watch said.

"Unfortunately, we saw last year that the United Arab Emirates decided to suppress freedom of expression in the country by harassing and trying a number of activists, and by attempting to limit freedom of association in the country," HRW'S deputy Middle East head Nadim Houry told the conference.

Subsequently a group of men dressed in traditional Emirati clothing burst into the conference and demanded it end because Human Rights Watch did not have a permit to host such an event.

Attendees heard the men identify themselves as officials of the Ministry of Economy. They flashed an identification card, HRW researcher Samer Muscati, one of the conference's organisers, told Reuters, but they could not see it long enough to determine who had issued it.

"We speculate that these guys are not who they claim to be. They seem to be state security, not from the Ministry of Economy," he said.

Officials of the UAE Interior Ministry and the Dubai government's press office declined to comment on the identity of the men, in response to queries about the incident.

At least three of the Emirati nationals who had their citizenship revoked were present at the conference. They said the government had revoked their citizenship because they were calling for reform and were members of an Islamist organisation that had been registered with the government for decades.

The UAE has said the men had originally had the nationality of other countries, and had committed "acts threatening the national security of the UAE", saying some of the men had "connections with suspicious terrorism financing organisations".

"It's ironic that this happened as we were highlighting the issue of freedom of speech," Muscati said. "This incident shows us how much pressure local activists must feel trying to challenge the government on freedom of expression."

The group said it would seek an explanation of the incidents from UAE Prime Minister and Dubai ruler Sheikh Mohammed bin Rashid al-Maktoum, and called on the UAE to cease harassment of activists.

"We know that the UAE government has global ambitions and wants to be a global player," Houry said.

"But at the same time, it cannot achieve that ambition if its going to detain activists, disband organisations, and arbitrarily take away citizenships."