U.S. President Donald Trump said on Friday he has spoken with Australian Prime Minister Malcolm Turnbull and that they are working on an agreement so Australia will not be subject to U.S. tariffs on steel and aluminum.

"He is committed to having a very fair and reciprocal military and trade relationship," Trump said on Twitter, referring to Turnbull.

"Working very quickly on a security agreement so we don't have to impose steel or aluminum tariffs on our ally, the great nation of Australia," Trump said.

Despite being one of the world's largest suppliers of raw commodity, iron ore, Australia is a small global exporter of steel.

Australian steel and aluminium to the United States were worth just over 400 million Australian dollars ($314 million) last year, government data shows.

Shortly after Trump's tweet, Turnbull said on Twitter that the relationship between the two allies was fair and reciprocal.

"Thank you for confirming new tariffs won't have to be imposed on Australian steel & aluminium — good for jobs in Australia and in US!" he tweeted.