US President Donald Trump said on Friday that Russia should be allowed back into the G8 group of industrialised nations, which became the G7 when Moscow was suspended in 2014.

"I have been Russia's worst nightmare ... but with that being said Russia should be at this meeting. Why are we having a meeting without Russia being in the meeting?" Donald Trump said at the White House shortly before departing for the G7 summit, which will take place on Friday and Saturday in a town outside Quebec City, Efe news agency reported.