ST. JOHN'S, N.L. -- Premier Kathleen Wynne says Prime Minister Stephen Harper is playing politics by refusing to co-operate with Ontario's new pension plan, and warns voters will question his motives in the upcoming election campaign.

"It's a disappointing political move on the prime minister's part," Wynne said Friday after Finance Minister Joe Oliver sent a letter rejecting Ontario's request for federal help in administering its new pension plan.

"I have no idea why Prime Minister Harper would want to make one of his last actions before he goes into an election -- or maybe one of his last actions as prime minister -- obstructing the retirement security of the people of Ontario," added Wynne.

Speaking after the annual premiers' conference in Newfoundland and Labrador, Wynne said her colleagues agreed to again look at enhancing the Canada Pension Plan, which remains her preferred option over creating a provincial plan.

"It is a live discussion across the country," she said. "It's not just about Ontario."

The federal government has the infrastructure to administer the CPP, and Ontario believes a fee-for-service agreement with Ottawa would be the most efficient way to implement its pension plan. The province said it is looking at other options.

Wynne vowed to proceed with its implementation, even without assistance from the Conservative government.

"I think it's very unfortunate, because what it does is threaten to make the whole process more complicated," Wynne said. "That is a real challenge for the people of Ontario to understand why the prime minister would want to make a process being put in place to make their retirement more secure more complicated."

The Conservatives have made no secret of their opposition to an Ontario pension plan, but Oliver upped the ante Thursday with his letter warning Ottawa will not co-operate with the province in any way.

"The Ontario government's ORPP would take money from workers and their families, kill jobs and damage the economy," wrote Oliver. "Administration of the ORPP will be the sole responsibility of the Ontario government, including the collection of contributions."

Ontario PC Leader Patrick Brown said his federal cousins were right to try and block the ORPP because of the costs it would impose on businesses, noting 150 companies signed a letter saying the pension, energy prices and a proposed cap-and-trade system are creating a hostile climate for businesses.

"When you see companies like General Motors and Ford signing that letter, saying this will kill jobs in Ontario, we should all be concerned," said Brown.

Oliver said the feds would also refuse any legislative changes for the provincial pension to be treated like the CPP and would not integrate it within contribution limits for Registered Retirement Savings Plans.

Under the Ontario pension plan, which was approved in legislation in April, workers will have to contribute 1.9 per cent of their pay, to a maximum of $1,643 a year, which employers will have to match for every employee.

The mandatory contributions will be phased in over two years, starting with larger companies in 2017 before expanding to include small operations like convenience stores and dry cleaners.