German Chancellor Angela Merkel said Donald Trump was isolated on climate change at the Group of Seven meeting on Friday, as the US president said he's in no rush to decide whether to scrap his country's involvement in the Paris Agreement.

A closed-door session on the first day of the G7 summit in Sicily found unity on stepping up efforts to combat terrorism, but entered stormier waters on trade and on climate, Mrs Merkel said. At that stage it was six against one as leaders pressed Trump to hold to US agreements made under the landmark Paris climate accord.

"We made it clear that we want the US to stick to its commitments," Mrs Merkel told reporters after the meeting on Friday. "There were very different arguments from us all urging the president to hold to the climate accord." She said the discussion was conducted in a very "honest" atmosphere, leading to a "very intense exchange."

After deriding climate change as a hoax and pledging to pull out of the Paris deal during his election campaign, Mr Trump has sidestepped the issue and passed up an number of opportunities to outline his international stance toward global warming. Members of his administration are deadlocked about whether the US should uphold the pact.