By John Irish, Jarrett Renshaw and Andreas Rinke KANANASKIS, Alberta (Reuters) -Group of Seven leaders faced early challenges during meetings in Canada on Monday as U.S. President Donald Trump said removing Russia from the former Group of Eight over a decade ago had been a mistake.

Donald Trump said it was a “big mistake” to exclude Russia from G7 summits as he used his opening remarks of the meeting in Canada’s Rocky Mountains to lament the group’s treatment of Moscow.

As the Group of Seven (G7) leaders gathered for a summit in Canada on Monday focusing on conflict and trade, US President Donald Trump bemoaned the exclusion of Russia. Ahead of the official start of this year's G7 summit of leading democratic economies in Canada,