US President Donald Trump has praised Australia's "Illegal Immigration" policy just hours before he is due to meet Prime Minister Scott Morrison for dinner at the G20 summit in Japan.

"These flyers depict Australia's policy on Illegal Immigration. Much can be learned!" Mr Trump tweeted on Thursday morning local time.

Included in the tweet, which has been liked over 13,000 times and retweeted over 4,000 times, were four Australian government advertisements published by the Department of Home Affairs overseas to deter people smugglers and asylum seekers from using boats to travel to Australia.

"No way," reads one advert. "You will not make Australia home. The Australian Government has introduced the toughest border protection measures ever."