The U.S. Embassy in Yemen has received information that a terrorist attack against U.S. interests in Yemen might occur as early as Tuesday.

A notice posted Monday on the embassy's Web site said there were no details as to the possible target, adding that the embassy is taking a number of security measures beyond those already in place.

It said the embassy is temporarily suspending immigrant visa and routine American citizen services to the public on Tuesday. It will be open to emergency American citizen services only.

The notice said the embassy is continuing to urge American citizens in Yemen "to maintain their vigilance and take appropriate steps to lessen their vulnerability."

It added that Americans should continue to keep a low profile, vary routes and times of travel, and avoid large crowds and demonstrations.

Last week, the embassy in Yemen as well as other U.S. diplomatic installations in the Middle East alerted Americans that large demonstrations and other incidents, sometimes violent, were taking place in the area.

It cited the increased tensions between Israel and the Palestinians as the reason.

Last week's notice said U.S. Embassy dependents located at several posts in the region had been authorized to depart voluntarily as a result.