CBCNews.ca is carrying the event live.
One of the activists, a male, was holding a sign that read "Climate justice now."
The second activist, a female, held up a sign saying "The Conservatives take climate change seriously." The sentence was crossed out.
Ian Black, the president of the board of trade, was introducing Harper when the activists took the stage.
Both men kept their cool as the pair were escorted off by security.
A press release from Brigette DePape, an anti-Harper protester, was issued immediately following the security breach.
"This morning two people directly intervened in a high security question and answer session with Prime Minister Stephen Harper regarding Enbridge’s Northern Gateway pipeline," the release said.
"The group managed to make their way past police undetected and into the secured Vancouver Fairmont Pacific Rim Hotel."
DePape was fired as a Senate page for after walking onto the Senate floor during a speech from the throne to protest against Harper's policies.
Harper is not expected to take any questions from the media.
The prime minister is expected to tout the benefits of the Comprehensive Economic and Trade Agreement with the European Union.