Duel British-American citizen, Nobel Prize winner John O'Keefe, spoke out about the U.K.'s immigration policies and policies on animal research, according to an article from the BBC. On Monday, O'Keefe was awarded half of the Nobel Prize for Physiology or Medicine for his research with rats that discovered "place cells," or a GPS map in the brain.

"I am very, very acutely aware of what you have to do if you want to bring people into Britain and to get through immigration, I'm not saying it's impossible, but we should be thinking hard about making Britain a more welcoming place," the BBC article quoted the 74-year-old as saying.

According to the article, Prime Minister David Cameron "has pledged to reduce net migration to less than 100,000 a year by 2015, while Home Secretary Theresa May has spoken about reducing it to tens of thousands."

O'Keefe also voiced his concerns on the British government's plan to "replace, refine and reduce" animal testing. His Nobel Prize-winning studies involved monitoring the brain cells of rats.

Parliament member Norman Baker told the BBC in July that he'd like to see all animal testing cease. "I am firmly of the belief it is not simply a moral issue but that we as a nation can get a strategic advantage from this - something that will be good for the economy."

O'Keefe disagrees.

O'Keefe told the BBC in his interview, "It is an incontrovertible fact that if we want to make progress in basic areas of medicine and biology we are going to have to use animals."

A spokesperson for the Home Office, the U.K.'s immigration and visa department, said "it is wrong to suggest our policies prevent companies appointing the skilled workers they need." According to the Home Office, an "exceptional talent" visa has helped skilled people enter the U.K. to fill job openings.