Austria's first coalition between conservatives and Greens announced Thursday that it would aim for carbon neutrality by 2040 to make the country a European "forerunner" in climate protection.

The two disparate parties have agreed to govern in what Greens leader Werner Kogler called a "gamble" after key election gains in September.

Their alliance means People's Party (OeVP) leader Sebastian Kurz, 33, returns as chancellor after his previous coalition with the far-right broke apart earlier this year owing to a corruption scandal.

It marks the first time the Greens enter government on a national level though the OeVP holds on to controversial anti-immigration measures that have deeply divided Austrians.

"It's worth the gamble" to work with the conservatives, Kogler told reporters when presenting the government programme.

The carbon neutrality goal - meaning greenhouse gas emissions are balanced with measures that absorb or eliminate carbon - is ahead of Europe's 2050 ambition.

But the 300-page government programme also highlights security needs, the conservatives' main campaign platform. "Migration will stay at the heart of my politics," said Kurz, who has styled himself as a tough anti-immigration fighter, reiterating his view that the coalition's parties had "succeeded in uniting the best of both worlds".

European Council President Charles Michel said 2020 began with "great news from Austria".

He tweeted: "25 years after its accession, Austria renews its commitment to the European project and is set to become a leader in the fight against climate change."

Observers say Germany and other nations could follow suit for the unlikely marriage of conservatives and ecologists as politicians seek to cater to voters' increasingly populist sentiments as well as worries about climate change.

But many have also warned that the alliance stands on thin ice as particularly the Greens have made key compromises.

A column in the left-leaning Standard on Thursday described the coalition as a "daring experiment" and a "political adventure". Tabloid Oesterreich billed the OeVP as "powerful as never before".

Kurz announced his party would head 10 ministries, including the interior, foreign, defence and finance.