Boris Johnson will travel back to Glasgow tomorrow in a last-ditch bid for progress at the COP26 climate summit.
The Prime Minister is expected to head back to the summit on Wednesday kick-start negotiations amid gloomy warnings about progress in efforts to halt the climate crisis.
A No 10 spokesman said: "The Prime Minister is going up to meet negotiators, to get an update on progress in the talks and encourage ambitious action in the final days of the negotiations."
Mr Johnson attended the first two days of the COP26 summit at the start of November but returned to London, leaving negotiators to try to hammer out progress.
He came under fire for jetting back from Glasgow by charter plane to attend a dinner at a member's club in London - after lecturing world leaders on keeping emissions down.
It comes as COP26 President Alok Sharma warned there was still a "mountain to climb" to keep global temperature rises below 1.5 degrees Celsius.
With only days to go until the summit wraps up, the commitment to keeping global warming below dangerous levels appears to be in jeopardy.
Mr Sharma told reporters that the first draft of the so-called cover decision, which summarises the commitments of more than 190 countries attending the summit, would be published shortly.
"We are making progress at COP26 but we still have a mountain to climb over the next few days," he said.
The UK's top scientist Sir Patrick Vallance said the goal to limit temperature rises to 1.5 degrees was non-negotiable but admitted it would be tough to meet.
He said: "It's crucial that the 1.5C is kept alive. I don't think this is a negotiable thing. It has to happen."
The Chief Scientific Adviser, who has previously warned that people will need to change their habits to tackle climate change, warned of the need to make behaviour change the easy choice.
"Behaviour change is part of this, and some of that is down to what we do as individuals and some of it is what needs to happen to make things easier for us," he said.
"We can't assume it's going to be dramatic personal behaviour change that's going to be the solution to this unless we make some way to of making that easier so that the green choice is actually the easy choice."
The latest national plans by countries for action on cutting emissions this decade still overall leave the world far off track for the 1.5C goal.
So negotiators are attempting to thrash out a "cover decision" from Glasgow, setting out how countries will close the gap between the plans to cut emissions in this decade and what is needed to avoid temperature rises of more than 1.5C, but how ambitious that will be remains to be decided.
