Theresa May urged fellow world leaders including Donald Trump to strive for “international cooperation and compromise” as she prepared for her final global summit as prime minister.
The PM will join counterparts in Osaka for the G20 summit against a backdrop of increased tensions over Iran’s activities in the Middle East.
She will also meet Russian president Vladimir Putin in the margins of the summit, which takes place on Friday and Saturday in the Japanese city.
The G20 will cover issues including climate change, global trade and efforts to prevent terrorists using the internet to spread propaganda.
Ahead of the summit, Mrs May said: “Undoubtedly there are issues facing us today on which our countries do not all take the same approach.
“But I firmly believe that progress will be greatest when we approach shared challenges in a spirit of genuine collaboration.
“As we have seen time and time again – we are always stronger when we work together.
“And so my message to G20 leaders this week is this: it is only through international cooperation and compromise that we can protect our citizens’ security and prosperity and make the world a safer and a better place to live.”
The US president is at odds with Western allies including Mrs May over climate change and the Iran nuclear deal, and Mr Trump’s trade dispute with China is also a concern to major economies in the G20.
Mr Trump and Chinese premier Xi Jinping are expected to meet in the margins of the G20 summit.
At the Osaka gathering, Mrs May is expected to make interventions on climate change – pushing other countries to go further following the UK’s commitment to cut greenhouse gas emissions to net zero by 2050 and lobbying for the UK and Italy to host the major COP26 international summit in 2020.
She is also set to push for action to tackle terrorists’ use of the internet, including removing harmful content within one hour of it being uploaded and ultimately preventing new content – including live streaming – being made available to users in the first place.
Mrs May said: “With the threat of climate change putting future generations at risk, vile terrorist propaganda continuing to spread online, and rising tensions in the Gulf, this summit is an opportunity for us to address critical global challenges affecting our nations.
“The UK has never been afraid to defend our values and our interests, stand up for global rules and tackle difficult issues head on.
“From our ambitious plans to protect the environment and our relentless fight against extremism in all its forms, to our promotion of free and fair trade and our world-leading international development expertise – we have consistently shaped global responses to the most pressing challenges of our time and called on others to step up and do more.”
The gathering of world leaders comes at a critical time for the Iran nuclear deal known as the Joint Comprehensive Plan of Action, with the UK and other allies desperate to keep it alive despite Mr Trump’s decision to pull out of the agreement.
Tensions in the region have increased since the attack on two oil tankers earlier this month, which the UK has said was almost certainly the work of Iran’s Islamic Revolutionary Guards Corps.
The downing of a US drone has added to the volatility, with Mr Trump calling off a retaliatory air strike with minutes to go.
Mrs May said: “The international community must stand together against Iran’s deeply destabilising activity.
“Our priority should be the urgent de-escalation of tensions and we need to find a diplomatic solution to the current situation.”
The US president’s approach to the Iran nuclear deal, and his decision to pull out of the Paris climate accord, have led to some “forthright” discussions between Mrs May and Mr Trump, according to a senior British government official.
“She has been very forthright in her views on both of these issues in her meetings with the president,” the official said.
Meanwhile, Downing Street stressed that the meeting with Mr Putin on Friday did not represent a normalisation of relations with Moscow.
The relationship with the Kremlin has been in the deep freeze since the Salisbury nerve agent attack on Sergei and Yulia Skripal in March 2018, which was blamed on Russia’s GRU intelligence agency.
“We remain open to a different relationship but that can only happen if Russia desists from actions which undermine international treaties and collective security,” the Prime Minister’s official spokesman said.