Germany’s Greens have signalled that negotiations to form a new governing coalition are progressing slowly and differences remain over climate policy.

The environmental party last month entered negotiations with the centre-left Social Democrats and the business-friendly Free Democrats on a new government after all three parties made gains in Germany’s September 26 election.

The alliance, in which Social Democrat Olaf Scholz would become chancellor, would send outgoing chancellor Angela Merkel’s centre-right Union bloc into opposition.

The parties said at the time that they hoped to have a coalition agreement ready at the end of November and have Mr Scholz take office in the week beginning December 6.

But the Greens are raising questions over whether that timetable will hold.

The party’s general secretary, Michael Kellner, told news agency dpa on Thursday that “we are seeing too little progress at the moment as far as substance is concerned”.

The Greens’ co-leader Annalena Baerbock told RBB Inforadio on Friday that she cannot say when a coalition agreement will be ready because it is not yet clear when negotiations on several central issues will wrap up.

She said: “It doesn’t come down to four days more or less in the talks – we must take the time we need so that we can really renew Germany in the next four years.”

It is no surprise that the negotiations, which outwardly have been unexpectedly harmonious, are proving tricky.

The potential alliance brings together two traditionally left-leaning parties with one, the Free Democrats, that has tended to ally with the centre-right.

A preliminary agreement last month left a lot of open questions. It called for Germany to accelerate its exit from coal-fuelled power, currently due by 2038, so it “ideally” happens by 2030, and speed up “drastically” the expansion of renewable energy generation.

The prospective partners said they won’t raise taxes or loosen curbs on running up debt, at the Free Democrats’ insistence, making financing a central issue.

Ms Baerbock would not detail where exactly there are differences. But she said that protecting the climate must be a priority across the government, including policy areas such as construction and transport.

“A climate government can’t be carried by only one partner,” Ms Baerbock said.