The parents of two Americans killed in a 2012 attack on a US mission in Libya have filed a lawsuit against Democratic presidential nominee Hillary Clinton, alleging that her use of a private email server contributed to the death of their sons.

Larry Klayman, the founder of the political advocacy group Freedom Watch USA, filed the lawsuit on Monday on behalf of Patricia Smith, the mother of US State Department employee Sean Smith, and Charles Woods, the father of navy SEAL Tyrone Woods.

The two Americans, along with a third staffer and US Ambassador to Libya Christopher Stevens, were killed in September 2012 when an armed mob attacked and set fire to the US diplomatic compound in Benghazi during a protest against an amateur film deemed offensive to the Prophet Muhammad.

The lawsuit blames Clinton, then US Secretary of State, for the deaths as well as for defamation and intentional and negligent infliction of emotional distress.

Benghazi attack report slams US State Department

The lawsuit says that fighters were able to "obtain the whereabouts of Ambassador Christopher Stevens and thus the US State Department and covert and other government operations in Benghazi, Libya, and subsequently orchestrate, plan, and execute the now infamous September 11, 2012 attack".

In addition to the wrongful death and negligence charges named in the lawsuit, the parents also claim that Clinton defamed them in statements to the media, according to the court statement.

"During her campaign for President, defendant Clinton has negligently, recklessly, and/or maliciously defamed Plaintiffs by either directly calling them liars, or by strongly implying that they are liars, in order to protect and enhance her public image and intimidate and emotionally harm and silence them to not speak up about the Benghazi attack on at least four separate occasions," it added.

Patricia Smith, one of the plaintiffs, has repeatedly spoken out against Clinton.

At the Republican National Convention on July 18 she said that she blamed Clinton "personally" for her son's death.

Smith and Woods v Clinton Complaint by LawNewz on Scribd

No evidence of Clinton wrongdoing

In June, however, a long-awaited congressional report blamed the Obama administration for lax security, but did not find any new evidence of wrongdoing by Clinton.

The 800-page report criticised senior officials in Washington, saying requests for extra security in Benghazi were repeatedly refused or ignored. It also said that the US military did not carry out orders from then Defence Secretary Leon Panetta to send US troops to rescue the Americans under attack.

The Benghazi issue has been used repeatedly by Republican presidential hopeful Donald Trump on the campaign trail to attack Clinton.

Clinton is the first woman to be nominated by a major party in America's 240-year-old history and has recently surged in the polls following a series of gaffes by Trump.

Source: Al Jazeera