"There is a high threat from terrorism. We believe terrorists may be planning to carry out attacks in the U.A.E.," a official travel notice on the office's Web site said.

The foreign office didn't provide details about why it thought a more serious threat was possible than the general one issued before to British nationals, the BBC reported.

Expatriates are a majority of the population of the oil-rich the United Arab Emirates, made up of seven emirates, including Dubai and Abu Dhabi. It is also a major tourist destination.

The warning said attacks could happen any time and could target residential compounds, military, oil, transport and aviation interests.

"You should maintain a high level of security awareness, particularly in public places," the advice says.

The warning was prefaced by a statement that the "vast majority of visits" to the United Arab Emirates are "trouble-free."