Columnists Charles Krauthammer called President Obama's claim Tuesday that he had no knowledge of any government officials being threatened for giving information about the Benghazi consulate attack "slightly incredible," during a panel discussion on "Special Report."

Fellow Fox News panelist Kirsten Powers called Obama's denial more evidence his administration does not take Benghazi seriously.

Fox News reported Monday at least four officials in the State Department and CIA were in the process of retaining lawyers or had already done so as they prepared to divulge sensitive information about the assault to Congress. Victoria Toensing, a former Justice Department official and Republican counsel to the Senate Intelligence Committee representing one of the State Department employees, told Fox News her client and some of the others, who consider themselves whistle-blowers, have been threatened by unnamed Obama administration officials.

But Obama, under questioning from Fox News' Ed Henry, claimed to not be familiar with anybody being blocked from testifying or that that any whistleblowers had sought legal counsel.

Krauthammer was highly incredulous of Obama's response, given Fox News' extensive coverage of Benghazi and the subsequent investigation into the attack that killed four Americans Sept. 11, 2012.

"Nobody at the White House has access to Fox News?" he asked. "This is slightly incredible, and it's a rather weak response for the president. He knew he was going to be calling on Ed Henry as the first question, because of his role [as president of] the White House Correspondents Association. He knew that Fox, or at least his staff knew that Fox had broken the story, spent a lot of effort on this story and time on the story last night. And he pretends he never heard of it? Call me skeptical."

Powers said it was very possible Obama's claim was true because his administration has never taken Benghazi seriously.

"They may have also not told the president about it, because they don't want him to have to answer any questions about it," she said. "This is a White House that actually has a pretty storied history of intimidating whistleblowers and prosecuting whistleblowers. It's not something the president is going to want to talk about."

Obama also repeated his claim Tuesday that his administration would bring the perpetrators of the Benghazi attack to justice. Nearly eight months afterwards, no one has been held responsible.

A 46-page House Republican report released last week included accusations that government officials purposely altered talking points about the attack to remove references to participation of al-Qaeda or Islamic extremists.

