All of the New Democrat membership applications that are being investigated by the Saskatchewan NDP were paid for by the Dwain Lingenfelter campaign, the party says.

Party officials spent the weekend investigating 1,100 applications after concerns were raised in the Meadow Lake constituency.

"We have found people who wanted memberships and people who did know this had been done on their behalf," Saskatchewan NDP CEO Deb McDonald said.

The applications under scrutiny all came in before April 24 — the deadline for people to sign up if they wanted to vote for the party's new leader.

Some of the applications came from the Flying Dust and Waterhen Lake First Nations, but the exact number hasn't been tallied, McDonald said.

Lingenfelter, a former deputy premier and former oil company executive, is one of four people running for leadership of the party. Also in the race to replace NDP Leader Lorne Calvert are Deb Higgins, Ryan Meili and Yens Pedersen.

The NDP leadership committee spent the weekend contacting applicants to find out whether they really wanted to be members of the NDP — and some didn't, McDonald said.

"The Lingenfelter campaign paid for all of them," she said.

For now, the 1,100 memberships are on hold.

"We haven't done any processing on these," she said. "If we find that these … weren't processed properly, or indeed, these people didn't want memberships, there are a whole variety of things. We won't even put them into the database at all."

The party rules allow for people to have their memberships purchased for them by someone else. Asked how that could happen without their knowledge, McDonald said there are a number of scenarios.

"Someone could have sat down with a phone book," or an old membership list, she said.

The party wants to resolve the issue quickly, McDonald said. The leadership convention is on June 6 and advance ballots will soon be sent out.

Lingenfelter wasn't available for comment.