More than 40 monkeys escape from a US medical lab

Forty-three monkeys have escaped from a compound used for medical research in South Carolina but the nearby police chief says there is "almost no danger" to the public.

"They are not infected with any disease whatsoever. They are harmless and a little skittish," Yemassee Police Chief Gregory Alexander said.

The Rhesus macaque primates escaped from the Alpha Genesis facility on Wednesday when a new employee did not fully shut an enclosure, Alexander said.

The monkeys are females weighing about 3kg and are so young and small that they have not been used for testing, police said.

Alpha Genesis employees "currently have eyes on the primates and are working to entice them with food," police said in a statement issued on Thursday.

The company usually handles escapes on site but the monkeys got outside the compound about 1.6km from downtown Yemassee, Alexander said.

"The handlers know them well and usually can get them back with fruit or a little treat," Alexander told the Associated Press by phone.

But rounding up these escapees is taking some more work.

Alpha Genesis is taking the lead, setting up traps and using thermal imaging cameras to recapture the monkeys on the run, the chief said.

"There is almost no danger to the public," Alexander said.

People living nearby need to shut their windows and doors so the monkeys can not find a place to hide inside and if they see the primates, call police so company officials and authorities can capture them.

Alpha Genesis provides primates for research worldwide at its compound about 80km northeast of Savannah, Georgia, according to its website.

The company did not respond to an email asking about Wednesday's escape.

In 2018, federal officials fined Alpha Genesis $US12,600 ($A18,900) after dozens of primates escaped as well as for an incident that left a few others without water and other problems with how the monkeys were housed.

Officials said 26 primates escaped from the Yemassee facility in 2014 and an additional 19 got out in 2016.