Days after the first Tasmanian devils immunised against a deadly facial cancer were released into the wild, two were killed on the roads.

The animals, with microchips, were released only last Friday. They were found dead on roads bordering Narawntapu​ National Park in northern Tasmania on Monday and Tuesday.

"Sadly, we were able to confirm the devils as two of the 20 released into Narawntapu on Friday night," Save the Tasmanian Devil program manager David Pemberton said.

"To lose two devils so soon after their release into the wild is devastating," he said.

It is the first attempt to repopulate devils in the wild after widespread losses because of devil facial tumour disease.

The captive-bred animals were among the first to be immunised against the cancer.

Despite the road deaths, the trial remained on track to providing valuable information on the effectiveness of the vaccine, a government statement said.

Devils often scavenged roadkill​ carrion, and their dark fur made them hard to see at night, Dr Pemberton said.

"The deaths highlight that roadkill is an ongoing threat to the endangered Tasmanian devil," he said.

Park patrols have been increased to remove roadkill that might lure devils onto the roads to feed, and feed stations have been set up away from roads.