OTTAWA — Ridding Afghanistan of corruption and improving the country's governance are more immediate challenges than military security, says America's top military commander -- even as the United States mulls committing another 30,000 troops.

Admiral Mike Mullen, chairman of the U.S. Joint Chiefs of Staff, continued to ratchet up international pressure on Afghan President Hamid Karzai during a working visit Tuesday to Ottawa.

Elections in Afghanistan are now set for Aug. 20, after repeated delays, and Canada and its NATO allies are preparing for a summer of violence linked to the national vote.

But Mullen, after meeting with Gen. Walt Natynczyk, Canada's chief of defence staff, stressed there is no military solution in Afghanistan.

"The lack of governance, tied to the corruption that exists, is going to be the No. 1 challenge that we have," Mullen told a news conference at National Defence headquarters before heading off to a meeting with Prime Minister Stephen Harper.

Military security is necessary, said Mullen, and a standing request for an additional 30,000 U.S. troops will be met with deployments mostly in the violent south and east of Afghanistan if, as expected, President Barack Obama gives the green light.

But, added Mullen, "I think we need to surge civilian capacity, if you will. ..."

"If we don't get the governance piece right -- and get it right pretty quickly -- then the security pieces are going to struggle to make any kind of significant difference. And that's a more important priority right now than the second piece."

The point was reinforced by Natynczyk, who said 2009 is "going to be a difficult year -- especially with the election -- but also a keynote year."

Natynczyk said Canada continues making headway training Afghan army and police, but there's a "big gap" in the country's governance.

"What we're really missing is a public service that makes the machinery of government work."

Amid rampant corruption, escalating violence and an endemic drug trade, Afghanistan's rulers have come in for increasing international criticism of late.

Defence Minister Peter MacKay acknowledged the critiques Tuesday, although he included Karzai among those expressing concerns rather than as one of the targets of criticism.

MacKay said there's widespread agreement on "the need to ensure that the Afghan government and the Afghan programs and the Afghan security forces are all pulling in the same direction and making good decisions."

"Now the election itself is coming up," MacKay said outside the House of Commons. "I expect it's going to be a competitive process but most importantly it has to be transparent, fair and inclusive of the Afghan people."

Natynczyk did not deny speculation that Canada may temporarily boost its military force in Kandahar by having an overlapping troop rotation there during the election period this summer.

"We're looking at a range of contingency plans ... to address the security needs for that election," he responded.

But both Natynczyk and Mullen emphatically denied they'd even discussed the notion of Canada extending its military commitment in Afghanistan beyond the 2011 end date set by Parliament last spring.

However, in remarks later en route to Washington, Mullen seemed to keep open a possibility Canada could change its mind about withdrawing its troops.

"2011 is a couple of years off," he said aboard his military plane.

"There's a lot that can happen. If in fact that's actually what gets executed, we're all going to have to adjust to that."

"They are a staunch ally, they've done exceptionally well in terms of providing the type of capability we need. And if that decision goes through, we're going to miss them," Mullen said.