Hillary Clinton’s representatives have refused to accept legal papers relating to the $50 million defamation lawsuit filed against her by Tulsi Gabbard, according to the Hawaii congresswoman's lawyer.

Ms Gabbard, who is currently seeking the Democratic party’s 2020 presidential nomination, filed the suit against Ms Clinton after the former secretary of state and 2016 presidential candidate insinuated that she was “the favourite of Russians”.

Brian Dunne, Ms Gabbard's lawyer, told the New York Post that a first attempt to serve the documents to Ms Clinton at her home in Chappaqua, near New York City, was rebuffed by Secret Service agents.

The server was instructed to deliver the documents to David Kendall, Ms Clinton’s lawyer in Washington, DC.

However, his firm, Williams & Connolly, also said it was unable to accept the papers.

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“I find it rather unbelievable that Hillary Clinton is so intimidated by Tulsi Gabbard that she won’t accept service of process. But I guess here we are,” Mr Dunne told the Post.

The basis for the lawsuit stems from an interview Ms Clinton gave in October in which she said that a Democratic presidential candidate was favoured by the Russians and may be groomed as a third party candidate.

Ms Gabbard was never mentioned by name, but when asked if Ms Clinton had been referring to her, spokesperson Nick Merrill said: "If the nesting doll fits..."

Responding on Twitter, Ms Gabbard called Ms Clinton: “The queen of warmongers, embodiment of corruption, and personification of the rot that has sickened the Democratic Party for so long…

“From the day I announced my candidacy, there has been a concerted campaign to destroy my reputation. We wondered who was behind it and why. Now we know — it was always you, through your proxies and powerful allies in the corporate media and war machine, afraid of the threat I pose,” she continued.

Mr Merrill was quick to reply, saying: “Divisive language filled with vitriol and conspiracy theories? Can’t imagine a better proof point than this.”

The lawsuit was filed on 22 January in the US District Court for the Southern District of New York.

It alleges that Ms Clinton's false assertions were made in a deliberate attempt to derail Ms Gabbard’s campaign.

While the suit does not mention a specific amount of damages, it does claim that Ms Gabbard has suffered “actual damages” of “$50 million — and counting”.