The group FEMEN Quebec claimed responsibility a few minutes later on social media, saying the act was meant to highlight its opposition to the Conservatives' proposed anti-terror bill.
FEMEN says the legislation criminalizes freedom of expression. One of its provisions makes it criminal to publicly applaud a terrorist act.
"The state becomes terrorist by creating these repressive, totalitarian measures," said Montreal's Neda Topaloski, who was banned from returning to Parliament for one year.
The wide-ranging bill would give police much broader powers and allow them to detain terror suspects and give new powers to Canada's spy agency.
The Conservatives introduced the legislation in January and have said it will make Canadians safer and give police and security forces the tools they need to meet terrorist threats.
Those opposed to C-51 say it would infringe upon Canadians' civil liberties and right to privacy, especially online.
Topaloski had time to yell her opposition to the proposed legislation before being ejected after a brief chase by security.
"I tried to stay as long as possible, grabbing on to things, but they ended up throwing me out," Topaloski told The Canadian Press not long after her expulsion.
Another group also held a protest in Ottawa against C-51, albeit a far tamer one.
Some protesters travelled from Toronto to offer hugs and flowers to MPs.
An organizer said the gestures were intended to help elected officials get over the trauma they might have experienced during the terror attack in Ottawa last year.
"They went through really terrible events on October 22 and we feel they are being guided by fear in legislating," said organizer Veronica Campbell.
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