Monkey business held up a Beijing-bound flight at Kennedy Airport nearly four hours yesterday.

A monkey escaped its crate in the cargo hold of an Air China Boeing 747 scheduled to leave Terminal 1 at 4:50 p.m., said Port Authority police.

Port Authority emergency services officers and an airport worker caught the monkey and handed it over to the airline. The animal never got out of the jet’s cargo hold.

The foot-tall monkey was one of about 50 to 60 being shipped to China for medical research, said police sources. “He was a slippery little beast,” one source said.