LETHBRIDGE, Alta. -- A spokeswoman for Alberta Premier Rachel Notley appeared to acknowledge the poor optics of a weekend appearance Notley made at a hospital, which the Opposition says broke rules prohibiting political activity at health facilities.

on Sunday that while Saturday's event was in a public area of the Chinook Regional Hospital in Lethbridge, the premier's office will ensure future campaign events are not done at Alberta Health Services facilities.

A picture Notley posted on Twitter of the event showed her standing at a podium with the message "Rachel Notley, fighting for you" on it, with health-care workers standing behind her.

United Conservative House Leader Jason Nixon said in a news release that Notley's NDP government and AHS should be investigated by the province's ethics commissioner for what he called a "partisan campaign event."

AHS policy states that elected officials may access their facilities for the purpose of carrying out their duties, provided they don't engage in political activity.

The health agency tweeted Sunday that the Notley event was not organized by AHS, and that participants were not representing the agency.

"The AHS Political Activity Policy, which came into effect in March 2012, is designed to maintain AHS's non-partisan role in health-care delivery, and to protect our staff and patients," the health agency said in a separate tweet Sunday.

An Alberta election must happen before the end of May, and Notley could call a vote at any time.

"The NDP's use of a public hospital to launch a partisan attack is an unethical abuse of public resources. Alberta's hospitals belong to Albertans, not to the NDP," Nixon said in his statement..

Nixon also suggested Notley and her staff broke government rules that prohibit them from using their influence to host a partisan event in a public hospital.

United Conservative Leader "an unethical abuse of public resources.

"Stop campaigning at public expense. Call the election," Kenney challenged Notley on Twitter.

Oates said on Twitter that "not a single tax dollar" went to the announcement.

"The nurses who came to speak out about the dangers of (Kenney's) plan to privatize health care, came on their own time because they are worried about what he will do to front-line services," she stated.

Kenney responded by posting that his party will maintain a "universally accessible, publicly funded health-care system."