US president-elect Donald Trump has aimed criticism at the European Union and Germany for their immigration policies, in a joint interview with Britain's The Times and Germany's Bild.

Trump said yesterday more countries could leave the European Union over immigration, and said Germany in particular had made a mistake letting in too many refugees.

"If refugees keep pouring into different parts of Europe... I think it's gonna be very hard to keep it together because people are angry about it," Trump said.

He said Brexit wouldn't have occurred if Britain hadn't been forced to take in so many refugees.

"People, countries, want their own identity and the UK wanted its own identity," he said. "This was the final straw that broke the camel's back... I believe others will leave."

Trump expressed admiration for German Chancellor Angela Merkel in the interview, but said she made a mistake by welcoming an unlimited number of refugees.

"I think she made one very catastrophic mistake and that was taking all of these illegals, you know taking all of the people from wherever they come from. And nobody even knows where they come from," Trump said.

He also told reporters from The Times and Bild that he would move quickly to seal a new trade deal with Britain and that British Prime Minister Theresa May would be visiting him "right after" he gets into the White House.

"We're gonna work very hard to get it done quickly and done properly. Good for both sides," he said.

- dpa