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NEW YORK, April 18 (Reuters) - New York police guarding the United Nations during Pope Benedict's visit on Friday made a rare discovery and rescue -- of a beaver struggling to swim past the world body's headquarters.

Soon after the pope left the United Nations, police harbor and scuba units patrolling the East River spotted the four-foot (1.20 metre) long, 40-pound (18-kg) animal. Beavers have only recently returned to the city with the first sighting of one in more than 200 years made in February 2007.

Lt. John Harkins, commanding officer, NYPD SCUBA, said in a statement that the animal had been tilting unnaturally and showed "labored breathing." After securing it in a safety noose the officers pulled it aboard their vessel.

"It has pretty big claws," Harkins said of the beaver which will be taken to an animal hospital.

The police harbor units were patrolling the river as part of the security effort for the pope's visit. (Reporting by Michelle Nichols, editing by Sandra Maler)