OTTAWA — The Canadian police on Monday began moving against protesters who had set up transportation blockades around the country in sympathy with an Indigenous group’s campaign to halt construction of a natural gas pipeline to Canada’s West Coast.

The blockades affected at least 19,500 rail passengers, according to Via Rail Canada, and 200 freight trains were unable to travel.

By late Monday, more than 47 protesters had been arrested. The nationwide demonstrations had been set off by the recent arrests of 21 protesters at the pipeline construction site itself.

The first blockade appeared on Thursday night and led to the shutdown of all rail passenger trains between Toronto, Montreal and Ottawa, as well as some freight trains. Another group was blocking freight and passenger rail traffic near Smithers, British Columbia.