Prime Minister Theresa May will challenge US President Donald Trump over climate change when they meet at the G20 summit in Germany.
She will say an international agreement on tackling climate change should not be renegotiated.
The talks on Friday will also focus on missile testing by North Korea.
Mrs May invited the president on a state visit to the UK but there was no mention of it in last month’s Queen’s Speech.
The prime minister expressed her “disappointment” when, in early June, Mr Trump pulled the United States out of the Paris Agreement, which calls on all nations to help stop the warming of the planet.
An official within the UK government said Mrs May was expected to raise climate change with the president at the meeting in Hamburg, and would stress that Britain “remains fully committed” to the agreement.
“She will say that we don’t see any need for renegotiation – we support the Paris Agreement because it delivers.”
Following North Korea’s latest missile test, the US said it will use its “considerable military forces” on that country “if we must”.
Britain has supported US calls for action against the threat, and Mrs May will tell the G20 meeting that it is “essential” the international community unites in condemnation of North Korea.
“Our focus is on working with the US and international community on how we can increase pressure and find a peaceful solution to the ongoing threat North Korea poses to international security,” the official added.
“We will continue to play a central role at the UN – supporting resolutions on sanctions that will limit North Korea’s ability to pursue its nuclear weapons programme.”