US military chief General Martin Dempsey denounced ex-officers Tuesday for waging a campaign against President Barack Obama, arguing that soldiers had a duty to stay above the political fray.

Wading into a potential minefield during a hotly contested White House race, Dempsey voiced his disapproval of a group of retired military members and CIA officers who have accused Obama of spilling sensitive national security details to help secure his re-election in November.

Asked if the group's criticism was valid or useful, Dempsey, chairman of the US Joint Chiefs of Staff, said he would not comment on the substance of their allegations.

But he added: "As to the latter, is it useful? No, it's not useful. It's not useful to me."

The military had a unique role that required political neutrality, said Dempsey, who spoke to reporters aboard his plane en route to the United States after visiting Afghanistan and Iraq.

"And one of the things that marks us as a profession in a democracy, in our form of democracy, that's most important is that we remain apolitical.

"That's how we maintain our bond and trust with the American people," the general said.

The group of ex-Navy SEALs and other retired officers who have blasted Obama, dubbed OPSEC for "operational security," insist they are not a partisan organization but have genuine concerns about national security leaks.

In videos aired this month, the group said the Obama administration endangered the United States and the safety of troops by allegedly disclosing secrets about operations, including the American raid last year that killed Osama bin Laden.

But Dempsey said those who serve or used to serve in uniform bear a special responsibility.

"The American people don't want us to be another special interest group. I mean they just don't want that. In fact, I think it confuses them," he said.

Dempsey acknowledged that the OPSEC group featured retired officers, but he said he believed the duty to stay out of party politics still applied.

"I know that these individuals to which you're referring are ex-military," he said.

"The problem is that when you use the military, I'm not speaking about them individually or specifically now, but if someone uses the uniform -- whatever uniform -- for partisan politics, I'm disappointed by that.

"Because I think it does erode that bond of trust we have with the American people."

Although the four-star general stressed the importance of a non-partisan military force, he will almost certainly be accused by some Republicans of taking sides in the presidential contest.

In the 2008 election campaign, Obama's team touted support from retired military officers while both parties in recent years have traded accusations of trying to exploit service members for political gain.