HALIFAX -- Nova Scotia's Progressive Conservatives have suddenly removed a candidate from one of three upcoming byelections for failure to comply with the party's disclosure rules under its selection process.

Tory Leader Tim Houston says Danny Laffin has been replaced as the Tory candidate in the Cape Breton riding of Northside-Westmount.

Houston isn't saying specifically why he replaced Laffin with Murray Ryan on Wednesday, adding only that his party "sets a high standard for those who can run under our banner."

He says Ryan is a chartered professional accountant with more than 25 years in senior positions as a finance executive.

Meanwhile, Elections Nova Scotia says nominations are now closed for the byelections in Argyle-Barrington, Northside-Westmount, and Sydney River-Mira-Louisbourg.

Voters will go to the polls on Sept. 3., and Laffin, an employee of the provincial Department of Transportation and Infrastructure Renewal, is now listed by Elections Nova Scotia as an Independent candidate.

"It came to a head this morning for sure, and the party made the decision to remove its endorsement," Houston said.

He said the party has a rigorous screening process that is based on trust.

"Something wasn't disclosed that should have been disclosed, and it ends up that it breaks the trust," Houston said.

In a short Facebook post, Laffin said he was resigning with a "heavy heart" as the Tory candidate.

"More information will be released after we seek legal counsel," Laffin said.