A former investigator with the congressional panel probing the deadly 2012 attack on the American mission in Benghazi, Libya is accusing Republicans of targeting presidential candidate Hillary Clinton.

Major Bradley Podliska is preparing to file a federal lawsuit against the House Select Committee on Benghazi next month, saying he was fired in part because he opposed the panel's decision to focus primarily on Clinton's role while she headed the US State Department.

The former secretary of state is the frontrunner in the Democratic race for the presidential nomination for 2016.

Podliska, an intelligence officer in the Air Force Reserve who describes himself as a conservative Republican, also claims he lost his job because he took leave for several weeks from the committee to fulfill his military service obligations, which would be an unlawful firing, if true.

"I knew that we needed to get the truth to the victims' families," he told CNN's "State of the Union" in an interview to air on Sunday.

"The victims' families, they deserve the truth -- whether or not Hillary Clinton was involved, whether or not other individuals were involved," Podliska said.

"The victims' families are not going to get the truth, and that's the most unfortunate thing about this."

Podliska served almost 10 months on the panel before he was fired in late June.

The committee, however, strongly disputed Podliska's claims. It insisted he was "terminated for cause" due to his own "improper partiality" against Clinton and other members of President Barack Obama's administration.

The committee said in a statement that Podliska had sought to use its resources to create a "PowerPoint 'hit piece' on members of the Obama administration -– including secretary Clinton." It added that the reasons for his firing were "directly contrary to his brand new assertion."

- 'Ugly chapter ' -

Critics accuse the House committee of conducting a biased, partisan probe of the September 11, 2012 attacks that killed US ambassador Christopher Stevens and three other Americans.

Last month, House Majority Leader Kevin McCarthy raised eyebrows when he welcomed the investigation resulting in any damage of the Clinton campaign.

"Everybody thought Hillary Clinton was unbeatable, right? But we put together a Benghazi special committee, a select committee," he told Fox News.

"What are her numbers today? Her numbers are dropping."

Podliska claims that after revelations first emerged in March that Clinton had used a private email server while serving as secretary of state, the panel's investigation became less comprehensive, focusing narrowly on the State Department's role in the controversy over the assault.

All but five of the 31 press releases the committee has released since that time have focused on Clinton.

The top Democrat on the panel, Elijah Cummings, said the "extremely serious" whistleblower charges show that "Republicans have been abusing millions of taxpayer dollars for the illegitimate purpose of damaging Hillary Clinton's bid for president."

Podliska told CNN that the panel -- chaired by Republican Representative Trey Gowdy -- diverted resources from investigations of other individuals and agencies to focus almost exclusively on Clinton and the State Department.

Clinton, who served as the top US diplomat for four years, is due to testify publicly before the committee for the first time on October 22.

The ranking Democrat on the House Intelligence Committee, Representative Adam Schiff, called for an end to the Benghazi panel, which has spent some $4.5 million so far.

"Only by ending this expensive and politicized investigation can we begin to undo the damage already done through this unprecedented use of Congress's power for nakedly political purposes," he said.

And the top Democrat on the House Armed Services Committee, Adam Smith, agreed. If the allegations are true, "we should slam the door shut on this ugly chapter in American history and close down the Benghazi Committee," he said.

President Barack Obama's administration initially said the attack was the spontaneous act of a mob enraged by a video circulating on the Internet that insulted Muslims.

But days later, the administration said the attack was in fact an act terrorism. Obama faced re-election less than two months' later.

Critics said the initial accounts -- which blamed mob violence rather than a premeditated terror attack -- sought to mislead the public and avoid angering American voters worried about terrorism.

The State Department has been releasing troves of emails from Clinton's time as secretary of state, some of which are on the subject of the Benghazi attack.
Source: AFP