Counterterrorism officials alerting state and local law enforcement about potential for attacks

WASHINGTON, D.C. - U.S. counterterrorism officials are growing concerned about threats from al-Qaida and other terror groups during the holiday season.

The FBI and Homeland Security Department encouraged state and local law enforcement to increase their awareness of suspicious behavior and to regularly change security measures to interfere with any terrorist plans.

The warning was sent in a bulletin and obtained by The Associated Press. It does not, however, include information about specific plots.

A number of attempted attacks against the U.S. in the past year, particularly a Nigerian man charged with trying to take an airplane last Christmas by igniting explosives in his underwear, has officials on high alert.

Captured insurgents in Iraq claim al-Qaida is planning attacks in the U.S. and Europe during the holidays.