A Danish politician says the delegation she is travelling with has cancelled its visit to Nauru after the Nauru government said some members of the group were not welcome.
In a Facebook post, Johanne Schmidt-Nielsen said on Monday the government had moved to exclude three members of the delegation.
The 48-hour visit of the Danish Parliament's Immigration Committee had been planned for some time, she said.
She and one of the other excluded politicians, Jacob Mark, had criticised Australia's asylum seeker processing in the media, Ms Schmidt Neilsen said.
But she said it was anybody's guess why the other politician, Naser Khader, was excluded, without having criticised Nauru or Australia.
Ms Schmidt Neilsen is from the Red-Green Alliance, Mr Mark is a member of the Socialist People's Party and Mr Khader is from the Conservative People's Party.
She said in her post that politicians from the Social Democratic Party, the Danish People's Party and Denmark's governing Liberal Party were told they were still welcome.
The Danish delegation cancelled the visit after Nauruan authorities announced their decision was final yesterday, she said.
"The government of another country should not be able to pick out members of a Danish parliamentary delegation.
"Such an action is deeply undemocratic," Ms Schmidt-Neilsen said.
Mr Mark told Radio Denmark he was amazed he was being denied access to camps controlled and run by Australia.
It was extremely undemocratic and he failed to understand how Australia could accept it, he said.
Danish foreign minister Kristian Jensen said he would fight for access for all the MPs to Nauru, adding that it was important to see the camps.
The trip was initially billed as a study tour of Australia's policy of processing asylum seekers abroad.
It came amid a growing debate in Europe over whether to adopt Australia's policy to deal with refugees from the Middle East and Africa.