"I assured the president that Russia was ready to maintain this transit route" for Russian gas, Putin said.

He was addressing concerns that the planned Nord Stream 2 line through the Baltic and Germany would put Washington's Ukrainian allies at a disadvantage.

Putin also suggested to Trump that Russia and the United States cooperate on regulating oil and shale gas production.

"We could work together in a constructive way to regulate the international markets because the extreme drop in prices is not in our interests," Putin said.

He spoke at a news conference alongside Trump in Finland after the two leaders' first ever joint summit.