Warning: distressing image below

US President Donald Trump and Australian Prime Minister Scott Morrison will not be lacking a conversation starter when they sit down for dinner at the G20 in Osaka, Japan.

Mr Trump took to Twitter aboard Air Force One on his flight to Japan on Wednesday to post four confronting anti-illegal immigration posters created by the Australian government in 2014.

Mr Morrison was Australia’s immigration minister at the time.

The posters are no longer used, but that did not stop Mr Trump, who is heading into the 2020 presidential election with security on the Mexico-US border as one of his top issues to win votes.

“These flyers depict Australia’s policy on Illegal Immigration,” Mr Trump wrote.

“Much can be learned!”

One of the posters features a photo of a boat on a rough, open ocean with the warning in red capitalised letters: “NO WAY. YOU WILL NOT MAKE AUSTRALIA HOME”.

These flyers depict Australia’s policy on Illegal Immigration. Much can be learned! pic.twitter.com/QgGU0gyjRS

— Donald J. Trump (@realDonaldTrump) June 27, 2019

Another says: “Australia’s borders are closed to illegal immigration”.

In 2014 human rights activists labelled the posters distasteful and embarrassing to Australia.

Greens Immigration spokesperson Senator Nick McKim on Thursday slammed the president’s tweet.

“We should be horrified that one of our most shameful policies is being applauded by one of the world’s cruellest leaders,” the senator said.

Mr Morrison backed the controversial posters on their release, describing them as part of a “targeted campaign”.

“This will complement the offshore communications campaign about the government’s strong border protection policies which comprises the overwhelming allocation of resources in which messaging is delivered directly through transit and source countries,” a spokesman for the minister said at the time.

Senator McKim said Mr Trump’s tweet “applauding Australia’s immigration policy tells us all we need to know about its cruelty”.

“This is mortifying in the extreme, but comes as no surprise after neo-nazi groups in Europe adopted and embraced the same propaganda last year,” the senator said.

“Trump is taking a leaf out of Australia’s book, and just as on Manus Island and Nauru it is innocent people and children who are paying the price with their lives and freedom.”

Mr Trump has been under fire for his administration’s treatment of illegal immigrants, with children separated from their parents and locked up in stark conditions.

A photo of Salvadoran migrant Oscar Alberto Martinez Ramirez and his nearly two-year-old daughter, Valeria, dead and lying face down on the bank of the Rio Grande in Matamoros, Mexico, brought a stark reality this week to the tragic end of some who attempt to cross illegally into the US.

The bodies of Salvadoran migrant Oscar Alberto Martínez Ramírez and his nearly 2-year-old daughter Valeria lie on the bank of the Rio Grande in Matamoros, Mexico.

After seeing the traumatic picture, Mr Trump said: “I hate it.”

“That father … was probably a wonderful guy,” he said.

“A very very dangerous journey. And by the way many other things happened. Women being raped; women being raped in numbers nobody believed.”

He added that the refusal by the opposition Democrats to back his border policies was to blame for deaths of illegal migrants.

“That’s what I’ve been saying: If they fixed the laws you wouldn’t have this,” he said.

Mr Trump calls the border crossings a national emergency and has requested $US4.5 billion in emergency aid to help law enforcement deal with “the historic surge in large migrant groups arriving at our southern border”.

Mr Morrison will be the first world leader to meet with Mr Trump at the G20.

They will have dinner on Thursday night.

On Friday, Mr Trump will meet Japanese Prime Minister Shinzo Abe, Indian Prime Minister Narendra Modi, German Chancellor Angela Merkel and Russian President Vladmir Putin.

On Saturday, he will hold his much-anticipated meeting with Chinese President Xi Jinping.

Mr Morrison backed the controversial posters in 2014, describing them as part of a “targeted campaign”.

“This will complement the offshore communications campaign about the government’s strong border protection policies which comprises the overwhelming allocation of resources in which messaging is delivered directly through transit and source countries,” his spokesman said at the time.

On Thursday, Greens Immigration spokesperson Senator Nick McKim slammed Mr Trump’s tweet.

“We should be horrified that one of our most shameful policies is being applauded by one of the world’s cruellest leaders,” he said.

-AAP