A coal power plant is seen during a thunderstorm in the western city of Weisweiler June 9, 2014. REUTERS/Ina Fassbender

BERLIN (Reuters) - Environmental policy dominated negotiations on forming a new German coalition on Monday, as the Greens pushed their would-be partners for a quicker exit from coal power.

Chancellor Angela Merkel’s conservatives, who lost seats in last month’s election, hope a deal with the pro-business Free Democrats (FDP) and the Greens will keep her in office, but the unlikely partners are far apart on a host of issues.

Merkel urged party leaders at the weekend to show more willingness to compromise after three weeks of exploratory talks also failed to paper over differences on transport, immigration and euro zone governance.

“What’s lying on the table isn’t enough for us,” said Greens chairwoman Simone Peter in response to a suggestion by the two other camps that 10 coal-fired power stations be shuttered. The Greens are holding out for carbon dioxide emissions cuts that would require the closing of 20 coal plants.

Earlier, a discussion paper seen by Reuters showed that the two more pro-business partners wanted to cut coal power by 3-5 gigawatts by 2020. The ecologists wanted an 8-10 gigawatt cut.

Peter told reporters that the Greens disagreed on the size of cuts in carbon dioxide emissions that were needed by 2020. The conservatives and the FDP believed cuts of up to 66 million tonnes were needed by 2020, while the Greens believed cuts of up to 120 million could be needed.

(This version of the story changes day to Monday in par 1)