Senator John McCain accused the White House of a "coverup" over Benghazi on Sunday, ratcheting up Republican pressure over the administration's handling of last September's consulate attack.

Speaking on ABC's This Week, the GOP grandee alleged that there had been a "wilful removal of information" over the attack in Libya, an assault that resulted in the deaths of four Americans including ambassador Chris Stevens.

In a further attempt to keep pressure on the administration, along with potential 2016 candidate Hillary Clinton, McCain called for the setting up yet another congressional committee to investigate the circumstances of the 11 September attack. He added that Clinton should be forced to testify again.

The apparent Republican focus on attempting to pin Benghazi on Clinton has been taken by Democrats as a blatant attempt to smear her ahead of a widely speculated run for the presidency.

Speaking on CBS's Face the Nation on Sunday, Democratic Senate majority whip Dick Durbin accused Clinton's detractors of playing politics.

"Unfortunately, this has been caught up in the 2016 presidential campaign, this effort to go after Hillary Clinton," the Illinois senator said.

He added that there was no coverup over the attack. Durbin went on to dismiss the discrepancies seen in different versions of the initial official statement on the attack as "a squabble between two agencies, the CIA and the State Department".

Renewed focus has been drawn to the initial reaction to the consulate assault after it emerged last week that State Department staff edited out references to prior terrorist threats from an original draft of a talking points memo.

According to reports in the US media some 12 different versions of the document were produced.

The first, drawn up by the CIA alone, mentioned that there had been "at least five other attacks against foreign interests in Benghazi" in the months leading up to the deadly attack.

But emails have revealed that State Department spokeswoman Victoria Nuland objected to the paragraph, commenting that it "could be abused by members (of Congress) to beat up the State Department for not paying attention to warnings".

The line was removed.

Republicans have long contended that statements from the administration after the attack were construed to minimize any blame over a perceived lack of security at the consulate.

Susan Rice, US ambassador to the UN and a former frontrunner to replace Clinton as state secretary, saw her political ambitions cut short after she suggested that the attack could have originated from a spontaneous protest over an anti-Muslim US-made film.

Rice had based her comments on the talking points supplied to her from the State Department and the intelligence services.

Despite a number of congressional bodies having already held sessions into the incident, Republicans appear intent on pushing for another investigation by a joint select committee.

"It requires a full and complete ventilation of these facts," McCain said Sunday. It is thought that the longer the issue drags on, the more damaging it could be for both the White House and Clinton.

The former first lady has yet to say whether she will run in 2016. But given her popularity among Democratic colleagues and the party base alike, it is thought that she would be a strong favourite to take the candidacy should she mount a campaign.

Some Republicans, including former House speaker Newt Gingrich, have openly aired their concern that a run by the former secretary of state, backed by President Barack Obama, could be unstoppable. It is with that in mind that many of her opponents are hoping to pin some of the blame for Benghazi on the then-secretary of state. © Guardian News and Media 2013