* Prime minister wraps up tour in Yukon

* Took similar trip before last election

* To visit dam site near the town of Mayo

By Allan Dowd

WHITEHORSE, Yukon, Aug 21 (Reuters) - Canadian Prime Minister Stephen Harper wrapped up his Arctic tour on an environmental note on Friday, ending a cross-country journey that felt like a tune-up for a possible election campaign later this year.

Harper, who promoted sovereignty, military and economic themes in the five-day trip across the Far North, was scheduled to sign a deal to help expand a dam that will help reduce Yukon's greenhouse gas emissions by about 50 percent.

But like all of the tour's earlier funding announcements, the hydroelectric upgrade, worth up to C$71 million ($66 million), was already in this year's federal budget, making the visit largely symbolic and a scenic background for photos.

Harper was to fly on Friday in a military transport plane to the site near the town of Mayo in central Yukon and to inspect the facility by air and land.

The prime minister's journey across the Far North has ostensibly been to emphasize Canada's Arctic sovereignty claims -- notably over the fabled Northwest Passage sea route -- but its staged events and daily messages aimed at a domestic audience seemed more like a tune-up for a fall election.

Harper has said he does not want to have an election any time soon, but the opposition Liberals have threatened to unveil a motion of non-confidence when Parliament returns next month, aiming to bring down the minority Conservative government.

Harper took a similar trip around Canada's Far North nearly a year ago -- including a flight to the Yukon -- shortly before he called an election that saw the Conservatives win a second minority government, albeit a stronger one.

An opinion poll released Thursday showed the Conservatives still slightly ahead of the Liberals, though neither of the two main parties would have a clear chance of victory if an election were held now.

The environment has been seen as a potential weakness for the Conservatives, whose power base is in the oil-rich western province of Alberta.

Some critics say the government has not done enough to reduce greenhouse gas emissions in order to protect the vast oil sands in northern Alberta.

Harper denies the allegations, saying the government's environmental plans go beyond those proposed by the United States.

The expansion of the Mayo hydro facility's generating capacity and a related electrical transmission system is forecast to reduce Yukon's need for diesel-powered generators by more than 40 percent, according to the government.

Ottawa will pay for its share of the C$160 million project from its C$1 billion Green Infrastructure Fund, designed to help pay for large environmental projects.

The public utility in the eastern Arctic territory of Nunavut, where Harper began his trip, also wants help replacing its aging diesel generators. Ottawa has rejected that call, saying funding power projects was the territorial government's responsibility.

($1=$1.08 Canadian) (Editing by Rob Wilson)

AlertNet news is provided by