The provincial New Democratic Party is investigating allegations that party memberships have been sold improperly in northern Saskatchewan.

The party's CEO, Deb McDonald, says the party has had phone calls from people in the north who expressed concern.

However, she wouldn't say what those concerns were or how many people had complained.

"We can't be sure the memberships that they're speaking about — whether it was only one camp that has sold these memberships," she said.

The party leadership committee will be meeting Friday night to discuss the issue and will spend the weekend investigating, McDonald said.

"We're going to take a look at these memberships and we'll phone some of the people and we'll talk to them and just check out with regard to how they obtained their membership — if they're happy with their membership, if they really wanted a membership — and just give them options," she said.

McDonald said she will also contact the four candidates about the memberships, although she wouldn't say whether any of them are implicated in the matter.

The four candidates in the party's leadership vote, set for June 6, are Deb Higgins, Dwain Lingenfelter, Ryan Meili and Yens Pedersen .

On Wednesday, the party put out a news release saying party memberships had tripled thanks to the excitement over the contest to succeed the party's current leader, Lorne Calvert.

McDonald said then that party membership now stands at 14,169. She said it shows people are "very interested" in the future of the NDP.

Political parties typically sell a lot of memberships during leadership campaigns, the result being that supporters of particular candidates can vote for them.