A worker prepares a sign ahead of the G7 summit at a satellite location in Banff, Alberta, Canada

AP Banff (Canada)

Leaders of some of the world's biggest economic powers will arrive in the Canadian Rockies on Sunday for a Group of Seven summit overshadowed by a widening war across the Middle East and US President Donald Trump's unresolved trade war with allies and rivals alike.

Israel's strikes on Iran and Tehran's retaliation, which appeared to catch many world leaders unawares, is the latest sign of a more volatile world as Trump seeks to withdraw the US from its role as world policeman. Speaking on a flight to Canada to attend the summit, British Prime Minister Keir Starmer said he had discussed efforts to de-escalate the situation with Trump and Israeli Prime Minister Benjamin Netanyahu, as well as other world leaders.

Britain is sending Royal Air Force jets and other military reinforcements to the Middle East. "We do have longstanding concerns about the nuclear program Iran has. We do recognise Israel's right to self-defense, but I'm absolutely clear that this needs to de-escalate," Starmer said.