The New Democrats said that despite reaching out to International Development Minister Christian Paradis's office three times over the past few weeks, they still haven't received an invitation to attend next week's summit.
"I asked specifically to be invited. I’m the Official Opposition critic on international development," said Hélène Laverdière on CBC Radio's The House.
"I mean, this is a governmental event. I would presume many members of the Conservative caucus will find themselves there. So, are they turning it into a kind of partisan event where only Conservative MPs are entitled to attend?"
Laverdière said she finds it "worrying, to say the least."
"You know, it reminds us of trips abroad where only Conservative MPs were invited to participate," she said. "That is politicizing and I’m worried about that."
Status of Women Minister Kellie Leitch told the CBC's Evan Solomon on The House that the government has invited "Canadians all over the country."
"[The summit is] something Canadians should be proud of and we’ve invited experts from all over the country, as well as internationally, and I think we’re going to have a fabulous discussion," she said.
"So, I’m not interested in the partisan politics either. I’m interested in getting great results," Leitch said, adding that she would be "delighted" to get Laverdière's input.
CBC News contacted Paradis's office to confirm whether or not summit invitations were sent to opposition parties.
Spokeswoman Sandrine Perion said the office "will have to investigate that" before responding.
It's not the first time the government has hosted a high-profile event without including opposition parties.
In February, the NDP and Liberals accused the Conservatives of politicizing a visit by spiritual leader the Aga Khan when the parties didn't receive invitations to his speaking event in Toronto, which was organized by the Prime Minister's Office.