Angela Merkel was captured reading a crib sheet of factual notes about Australia’s prime minister, Scott Morrison, as the pair sat down together at the G20 summit in Argentina at the weekend.

The German chancellor’s briefing notes contained a brief biography and photograph of Mr Morrison – Australia’s fifth prime minister since 2013 – in case she struggled for basic details about him.

The Liberal Party leader took office in August this year after his predecessor, Malcolm Turnbull, was forced out by party rivals.

Australian media reacted with amusement at the idea the German chancellor needed to be reminded who their country’s leader was, dubbing her printed notes a “cheat sheet”.

“Who is this? Australians can probably relate to Angela Merkel’s predicament,” ran one headline in The Sydney Morning Post.

Mr Morrison’s closest allies denied any embarrassment over the photos.

“Angela Merkel’s department, no doubt ... was simply ensuring that the chancellor was properly briefed,” said the country’s trade minister, Simon Birmingham.

Since Ms Merkel became German chancellor in 2005, Australia has had six prime ministers: John Howard, Kevin Rudd, Julia Gillard, Tony Abbott, Mr Turnbull and Mr Morrison.

Ms Merkel’s notes at the G20 meeting included a photo of Mr Morrison (EPA)

On Monday, the Liberal Party passed new rules to make it harder to depose its leader, as the ruling coalition grapples with sinking opinion polls ahead of next year’s general election.

A two-thirds majority will now be required to change an elected party leader, promising greater stability after the revolving door of five prime ministers in little more than five years.

“It has been to the great anguish of the Australian people, as they have seen this happen in the Labour and the Liberal party,” said Mr Morrison. “And they’re sick of it ... and it has to stop.”

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The Australian prime minister also met Donald Trump at the G20 summit on Saturday.

“You’ve done a lot of the things that they’ve wanted over there and that’s why you’re sitting right here,” the US president said.