Germany has rejected an offer by US President Donald Trump to invite Russian President Vladimir Putin to return to the G7, German FM Heiko Maas told the Rheinische Post.

Last month, Trump raised questions about the prospects for expanding the G7 to include Russia, which was expelled from the G8 following the annexation of Crimea in 2014.

But Maas said he did not see an opportunity for Russia to return to the G7 until significant progress was made in resolving the issue of Crimea and the conflict in eastern Ukraine.

According to him, Russia itself can make the greatest contribution to becoming part of the G7 again by contributing to the peaceful resolution of the Ukrainian conflict, Reuters reported.

Russia remains part of the broader G20 group, which also includes other emerging economies.

Maas described relations with Russia as currently difficult in many areas.