US President Donald Trump will attend a G7 summit with leaders of the world's major economies in Sicily, Italy, on the last leg of his first foreign trip.
US President Donald Trump Photo: AFP
A tough debate is expected on issues including trade and climate change.
The G7 consists of Canada, France, Germany, Italy, Japan, the UK and the US. The EU also has representatives.
Four of the group's leaders - including Mr Trump and British Prime Minister Theresa May - will be sitting around the table for the first time.
Fresh from his public dressing down of Nato leaders for not spending enough on defence, Mr Trump is expected to be just as ready to take on his G7 counterparts, the BBC's James Landale in Sicily reports.
There will be agreement on the need to do more to tackle violent extremism, and there will be serious discussion with Japan's prime minister about the threat from North Korea, BBC's correspondent said.
The summit comes just days after Monday's deadly bombing in Manchester in which 22 people - including children - were killed.
Mrs May is expected to urge world leaders to do more to combat online extremism, saying the fight against Islamic State is "moving from the battlefield to the internet".
Disagreements are most likely to come over climate change and trade, the BBC's correspondent there said. Mr Trump will be urged not to abandon the 2015 Paris agreement to tackle global warming; and he will resist moves to limit protectionism in global trade.
Speaking ahead of the summit, White House economic adviser Gary Cohn predicted a "fairly robust discussion" in Sicily, Reuters reports.
Addressing a Nato summit in Brussels on Thursday, Mr Trump warned that all members of the alliance should contribute more financially on defence.
"Massive amounts of money" were owed, he said, voicing a long-held US concern that others are not paying enough.
Nato states' contributions are voluntary and a target of spending 2 percent of GDP on defence is only a guideline.
The bloc later agreed that member-states would report back annually on defence spending to Nato.
It also said it would take a bigger role in the campaign against IS militants, but France and Germany have insisted the move is mostly symbolic.
The G7 summit brings Mr Trump's first foreign tour as US president to a close. Earlier in the week, he said he was "more determined than ever" to pursue peace in the world after meeting Pope Francis at the Vatican.
Before that, he vowed to help Israelis and Palestinians achieve peace, as he ended the Middle East leg of his tour.
He began his foreign trip with a two-day stop in Saudi Arabia over the weekend, urging Muslim countries to take the lead in combating radicalisation.
