A man who says he dated Christine Blasey Ford in the 1990s has suggested she lied to the Senate during her hearing.

The purported ex-boyfriend, whose name has been redacted, spoke out in response to statements she made before the Senate Judiciary Committee last Thursday after accusing Supreme Court nominee Brett Kavanaugh of sexually assaulting her in the 1980s.

In a sworn written statement, the man claimed to have directly witnessed Ford helping her "long-time best friend" Monica McLean prepare for a polygraph exam.

"Dr Ford explained in detail what to expect, how polygraphs worked and helped McLean become familiar and less nervous about the exam. Dr Ford was able to help because of her background in psychology," he said in the statement.

During the hearing, Dr Ford said she had never had discussions with anyone, besides her lawyers, on how to take a polygraph, nor had she offered tips to anyone on doing so.

McLean has denied the man's claims.

"I have never had Christine Blasey Ford, or anybody else, prepare me, or provide any other type of assistance whatsoever in connection with any polygraph exam I have taken at any time," she said in a statement relayed by lawyers Michael Bromwich and Debra Katz today.

Speaking to CNN, the retired FBI agent said the "allegations are completely false", adding that she's furious her reputation is now being called into question by a "lie".

"I have never had anyone assist me with the preparation of any polygraph. Ever. Not my entry polygraph, not my five-year reinvestigation polygraphs. Never. I am extremely angry he would make this up," she told the network.

The ex-boyfriend claimed he and Ford dated for around six years between 1992 and 1998, noting that he found her "truthful" and maintained "no animus towards her".

He said she "never brought up anything regarding her experience as a victim of sexual assault, harassment or misconduct". He also said she never mentioned Kavanaugh.

This part did not conflict with Ford's testimony, however, as she said she disclosed the alleged assault for the first time in 2012.

The ex-boyfriend also disputed Ford's lawyers' claims that she has a fear of flying.

"While visiting Ford in Hawaii, we travelled around the Hawaiian Islands including one time on a propeller plane. Ford never indicated a fear of flying."

He said she never expressed a fear of close quarters, tight spaces or places with only one exit, adding that she lived in a small, 46sq m Hawaii apartment.

This was in relation to Ford's testimony about suffering from claustrophobia. The alleged assault was revealed to her therapist and husband in 2012 after she insisted on having a second exit to her home, which her husband couldn't understand before she opened up about the alleged attack.

Prosecutor Rachel Mitchell noted Ford flies "fairly frequently for hobbies and … work".

She said: "She flies to the mid-Atlantic at least once a year to visit her family. She has also flown to Hawaii, French Polynesia and Costa Rica. She also flew to Washington DC for the hearing."