Alberta public sector unions have been warned that the government is contemplating legislation to break their contracts by delaying a reopening of wage talks until it gets advice from a panel on the province's finances.

On Tuesday, the NDP Official Opposition released an email sent to unions on May 16 by Athana Mentzelopoulos, the deputy minister for Alberta Treasury Board and Finance.

In the email, Mentzelopoulos said the government is considering a delay in reopening talks on public sector wages, as guaranteed in the final year of the current three-year contracts, due to the change in Alberta's economy.

"A delay may give government the time to make an informed decision on how best to approach the wage reopener arbitrations, based partially on advice from the MacKinnon Panel," Mentzelopoulos wrote.

"Government is interested in hearing your organization's thoughts on the delay as per the above noted purpose and is considering all available options up to and including legislation."

Finance Minister Travis Toews said the government is keeping its options open until the panel chaired by former Saskatchewan finance minister Janice MacKinnon reports in August.

"We believe that delaying arbitration is the right path forward, the responsible path forward," he said.

MacKinnon has advocated in the past for restraints on public sector salaries.

David Eggen, the NDP MLA for Edmonton-North West, said the letter from the deputy minister was sent to the United Nurses of Alberta (UNA), the Alberta Union of Provincial Employees (AUPE), the Health Sciences Association of Alberta (HSAA) and the Canadian Union of Public Employees (CUPE).

The Alberta Teachers' Association also received the letter.

"The UCP doesn't even try using honey. It's vinegar all the way," Eggen said. "They seem to be keen to follow the old conservative bully tactics of disrespecting our frontline workers, which only leads to labour unrest and ultimately more costly settlements."

Several major public sector unions, including the UNA and the AUPE, have provisions for a reopening wage arbitration talks in the final year of three-year contracts.

The UNA's collective agreement, which expires at the end of March 2020, had a provision to reopen wage talks and hold an arbitration hearing by the end of June if the employer and union could not come to a settlement.

In May, the government intervened prior to an arbitration hearing, asking for a delay. The arbitrator agreed and the Alberta Labour Relations Board declined to get involved, suggesting the UNA take its complaint to court.

The AUPE also agreed to a contract with two years of wage freezes with a reopening of wage talks in the third year. That process started in January for 13 union locals, including sheriffs, correctional officers, conservation officers, food inspectors, trades workers and general support workers who work for Alberta Health Services.

In that case, the government's attempt to delay was rejected by the independent arbitrator.

Wage arbitration meetings are scheduled to resume June 11 and a hearing must be held by the end of the month.

The situation with the ATA is different. Teachers concluded a two-year agreement prior to the election with a provision to have wages determined by an arbitrator. The deadline for a hearing is the end of September.