The UN rights chief said Monday that the far-right tilt of Austria's new coalition government marked a "dangerous development", and cautioned against "the peddling of fear" in European politics.

"I am very worried," the UN High Commissioner for Human Rights Zeid Ra'ad Al Hussein told AFP in an interview, cautioning that the new Chancellor Sebastian Kurz's decision to take hard-right positions on things like immigration to win support marked "a dangerous development... in the political life of Europe."

Austria's far-right Freedom Party (FPOe) was sworn in Monday as part of the new government, headed by Kurz and his conservative People's Party (OeVP).

Kurz took over the OeVP in May and yanked it to the right, securing his party first place in October elections. At 31, Kurz is the world's youngest leader.

"I am unsettled by what has happened in Austria in the last six months, that the former foreign minister (moved) hard-right on the issue of immigration and migrants rights so that he could basically secure the votes that had previously gone to Freedom Party in order to win the chancellorship," Zeid said.

Zeid criticised Kurz for what he termed "complete opportunism", and warned of the example the young chancellor was setting for other politicians around Europe.

"I think the demonstration effect to other leaders in Europe could be something that we need to pay a deep attention to," Zeid said.

Others unable to win at the ballot boxes with a purely hard-right approach might learn from Kurz's approach, he warned.

"You don't come from the hard right... You come from right of centre or centre, and (move) hard-right just on (hot button) issues to win support, and that is a dangerous development."

Zeid harshly criticised politicians across Europe willing to turn to "the peddling of fear as a means of getting to political office... and directing the blame at a particular target population."

He warned of the rise of a "sort of ethno-nationalism, chauvinistic nationalism" across Europe, and stressed that the continent had been beset by such ideas before.

"We just have to wind back 104 years (to before World War I) and we were there," he said.

"The extreme right really has to think very carefully (about) where they are leading their countries and the continent more generally."