NEW YORK (AP) – The New York Police Department was reducing its extra security procedures Saturday, a day after racheting up counterterrorism precautions due to an unsubstantiated threat against the nation’s largest city.

The NYPD had increased radiological monitoring and established checkpoints to examine vehicles in lower Manhattan and at other locations around the city on Friday night. By noon Saturday, the department was scaling back its efforts on a relatively quiet August weekend, said NYPD Deputy Commissioner Paul J. Browne.

Mr. Browne noted that the NYPD routinely uses radiological monitoring as part of its counterterrorism activity. The city did not increase its terror alert status in response to online chatter about a truck packed with radioactive material, although police deployed extra radiological sensors on street, water and air patrols.

Mr. Browne said Friday that the measures were “strictly precautionary,” prompted by an Israeli Web site report that online posts were made following a video featuring an American member of Al Qaeda threatening foreign diplomats and embassies across the Islamic world.

Homeland Security Department officials quickly said Friday that they had no reason to believe the comments presented a credible threat, and Mayor Bloomberg said the police response was standard procedure for when city officials receive “potential but unconfirmed threats.”