The US president extended the invitation during a phone call to Prime Minister Scott Morrison on Tuesday morning.

Mr Morrison attended last year's G7 meeting as a special observer at the invitation of French president Emmanuel Macron.

"Participation at the G7 for the second year in a row will give Australia another significant opportunity to promote our interests during highly uncertain times in the global economy," a spokesman for the prime minister said.

"It's important for Australians that we are there."

The G7 members are Canada, France, Germany, Italy, Japan, the United Kingdom and the US.

Mr Trump says this combination is outdated and wants to expand the group to also include Australia, Russia, South Korea and India as he seeks to combat China's economic clout.

The meeting will be held in September at the presidential retreat Camp David.

Australian Associated Press