The Copenhagen Zoo says that at least five joeys are being carried in the pouches of their two females.

The young devils, about the size of a walnut, were found when the females were pouch-checked by zoo staff last week.

Curator Flemming Nielsen said three were spotted in one female and another two in the other.

"This is the first ever full recorded breeding of Tasmanian devils in the northern hemisphere," Mr Nielsen said.

"Some will say that there has been breeding in other places in Europe or North America during time, but all have been associated with female devils being imported with tiny pouch young.

"And the breeding has never been repeated after the arrival in Europe or in North America."

The joeys are expected to spend about four months in the pouch and, all going well, could be visible to the public in September.

Two devils were sent to Copenhagen in 2006 to mark the birth of Tasmanian- raised Crown Princess Mary's first child Prince Christian.

Four more followed in 2009.

Mr Nielsen said the zoo could play a role in breeding a healthy population of the endangered species, which has had 80 per cent of its numbers wiped out by the deadly facial tumour disease.

"This breeding proves that it is possible to build a breeding population outside the Australian region," he said.