Via says roughly 2,000 passengers on trains to and from Ottawa, Toronto and Montreal are affected that started late Sunday afternoon.
The rail line was blocked by protesters that CN Rail spokesman Jim Feeny says were part of the Idle No More movement.
The Idle movement staged other protests Sunday in support of Northern Ontario First Nations Chief Theresa Spence.
She is staging a hunger strike to back her demand for a meeting with Prime Minister Stephen Harper.
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