CALGARY — Tensions are escalating between two rival women's hockey organizations, as the Canadian Women's Hockey League is challenging the National Women's Hockey League's rights to the trademark "NWHL" in Canada.

A CWHL spokesperson confirmed the challenge filed with the Canadian Intellectual Property Office.

The Ontario Women's Hockey Association, which operated a different National Women's Hockey League in Canada and the U.S. from 1999 to 2007, joined the CWHL's challenge.

"The contestation of the NWHL trademark . . . are standard business procedures designed to protect the CWHL's name and intellectual property rights within Canada," Sasky Stewart told The Canadian Press in an email Wednesday.

A challenge to the trademark hasn't been filed in the United States. The CWHL's move may be to block potential NWHL expansion into Canada.

The current four-team NWHL, based in the United States, has played one season. That league has until June 13 to counterfile.

"We have been advised by counsel that the opposition proceedings in Canada are without merit," NWHL commissioner Dani Rylan said.

The NWHL committed to pay its players with a salary cap of US$270,000 per team, which works out to an average of $15,000 per player.

The CWHL doesn't pay its players, and now faces pressure to do so to prevent players defecting to the U.S. league.

The CWHL rose from the ashes of the previous National Women's Hockey League which ceased operations in 2007. Now a five-team league with one in Boston, the Clarkson Cup championship trophy has been awarded for seven seasons.