The Green Party of Canada has launched a formal investigation into allegations of workplace bullying levelled against leader Elizabeth May by three former employees.

May, who also serves as MP for Saanich-Gulf Islands, asked the party to launch a third-party investigation after the Toronto Star reported on the allegations over the weekend.

The former employees accused May of several instances of verbal abuse, saying she yelled at them and put them down in front of colleagues.

May held an impromptu news conference in the lobby of Parliament in Ottawa to reaffirm she was not heeding calls to step down as party leader. May said she had received "overwhelming" messages of support in the wake of the allegations.

"A woman leader of a federal political party has to be tough. I do not regard having a backbone as a character flaw," she said. "I am staying on as leader, I'll be doing the work that our members and supporters want me to do."

May said she asked for the independent investigation so she could offer her own version of the events and leave it to someone independent to determine whether it constituted bullying.

"Not everybody likes me, and that's okay. I accept that, it's life," she said. "Not everybody is going to like everybody else, and the important thing is to have a respectful workplace, to be able to work together, to have arguments, disagreements, and continue on as a team."

The Green Party also swiftly responded to the claims on the weekend, defending May and saying she was being held to a different standard than male party leaders.

"The Green Party believes that as a female political leader, she is being held to a different standard than her male counterparts," the statement read. "A man with these qualities is admired for his leadership. A woman is portrayed as overbearing and bullying. These outdated gender stereotypes have no place in 21st century Canada."

The party summed up the allegations as "simply the statements of disgruntled former staff and their credibility should be viewed in that context."

The Green Party said the third-party investigation will be headed by Sheila Block from Toronto law firm Torys LLP, and it will last about two to four weeks.

The party said the investigation's findings will be released to the public once it's complete.