Officials at the Montreal's Olympic Stadium have notified police about an anti-immigration banner posted outside the building, where hundreds of asylum seekers are currently being temporarily housed.

Far-right group Atalante Québec is mounting a public campaign against what it calls "illegal migrants," posting banners in Quebec City and Montreal to get their point across.

One of the banners was posted some time late Sunday night or very early on Monday outside the Olympic Stadium, on one of the ramps along Pierre-de-Coubertin Avenue that lead to the esplanade. 

It was spotted by security guards and taken down Monday morning, said spokesperson Cédric Essiminy.

The Montreal police department's hate crimes unit is looking into whether the incident was criminal.

Similar banners were posted in Quebec City last week. On its Facebook page, Atalante Québec has posted a number of pictures showing the banners, which say "#remigration."

The word is one used by those who want immigrants to return to their countries of origin.

Montreal Mayor Denis Coderre called the sign "odious," saying he didn't want to give the act any more attention than it deserves.

"We are in a society of diversity," Coderre said. "Immigration, for us, is important."

A temporary welcome centre opened at the Olympic Stadium earlier this month to house the influx of asylum seekers crossing the Canada-U.S. border as they wait for more permanent accommodations in the short term, and for their asylum claims to be heard in the longer term.

According to the RCMP, in the first two weeks of August more than 3,800 people walked over the border into the province, compared to the 2,996 who crossed throughout all of July.