Washington - Secretary of State John Kerry on Tuesday denounced an "enormous amount of misinformation" about a deadly attack on a US mission in Libya amid a report four US officials are set to leak secrets.
Questions about the 11 September assault on the US mission in Benghazi in which four Americans were killed have refused to go away, with some Republicans convinced the Obama administration tried to cover up the circumstances.
Fox News reported on Monday that at least four State Department and CIA employees have now hired lawyers after being threatened by administration officials for planning to reveal sensitive information to Congress.
One military special operations member on Tuesday openly disputed the findings of an internal State Department probe, saying US forces were just a few hours away and could have intervened to halt the attack.
"I know for a fact that C-110, the EUCOM CIF, was doing a training exercise in... not in the region of North Africa, but in Europe," the operator, who was not named, told Fox News. "And they had the ability to act and to respond."
Ambassador Chris Stevens was killed along with three others, after militants linked to al-Qaeda stormed the mission and a nearby CIA compound. An internal probe ordered by former secretary of state Hillary Clinton found that no US forces would have got to Libya in time to stop the attack.
Kerry, who took over from Clinton, denied claims the State Department had failed to be transparent enough.
"Look there's an enormous amount of misinformation out there," he said, adding his chief of staff David Wade was now closely in touch with Congress to answer any lawmakers' questions.
"We're prepared to work openly and accountably to answer any of those questions. So we have to demythologise this issue and certainly depoliticise it. The American people deserve answers."
Acting deputy State Department spokesperson Patrick Ventrell also said the department was "not aware of any employees who have requested security clearance for private attorneys in connection with Benghazi."
And he said "the State Department would never tolerate or sanction retaliation against whistleblowers on any issue."
A Congress report last week faulted Clinton over the attack, saying she rejected requests for greater security even though it was known the mission was "vulnerable and unable to withstand an attack."
It also charged that the administration had failed to react to warnings of security risks in Libya after the fall of dictator Muammar Gaddafi.