03/11/2017 12:55 PM AEDT | Updated 03/11/2017 12:59 PM AEDT

Nick Xenophon Denies Explosive Claims He Was 'Abusive' From Former Staffer Jenny Low

Former staff member has exposed their "secret" seven-year relationship.

Nick Xenophon has denied the allegations from a former staffer.

Former federal senator Nick Xenophon has denied explosive allegations from a former staffer that he was "manipulative" and "controlling" during their secret" seven-year relationship.

Xenophon, who quit the Senate last week as he prepares to run for South Australia's state parliament, issued a strongly-worded statement on Friday in response to claims from Jenny Low, who worked in his office for several years.

Low is now running for SA's state parliament herself for the Advance SA party and told media that she and Xenophon had been together between November 2007 and June 2014.

"I was very young when the relationship began. Being my first long-term relationship, I thought the manipulative and controlling behaviours towards me were normal. I now know that it is not," she said at a media conference on Friday, following a story in The Australian.

"The reality is that a 48-year-old man in a position of power pursued a 23-year-old who was in a junior role."

Low claimed Xenophon kept their relationship a secret.

"It is not normal to be in a seven-year relationship with somebody and for his family not to know. It is not normal to have your existence denied to everyone you meet except a handful of trusted people," she told reporters.

In response to questions about why she was only airing the claims on the day of the party's election launch, Low claimed she did not want to talk about the issue at length, and was only responding to questions on the matter because of the story in The Australian.

In a statement on Friday, Xenophon said he was dismayed at the story and Low's allegations.

"I am deeply saddened that a failed long-term relationship that I was involved in has been used by the Advance SA Party for blatant political gain. The party should be renamed Gutter SA," he said.

"I absolutely reject and am most distressed by any suggestion my relationship with Jenny was abusive or predatory in any way, manipulative or controlling. I deeply regret that we couldn't make the relationship work."

Advance SA is led by MP John Darley, a former member of Xenophon's party. Low worked for Darley for 10 years before running for office under the party's banner.

"Mr Darley has never expressed any concerns to me about the relationship prior to today. That he now chooses to use my former relationship at his party's launch smacks of the lowest form of dirty and desperate political opportunism," Xenophon said.

"I'm deeply disappointed the level of political debate in our state has plummeted to such depths. When I entered this campaign I forecast my political opponents would throw everything at me including the proverbial kitchen sink. They clearly have not hesitated to get into the gutter at the first opportunity."