An internal WA Nationals review has reportedly found a sexual harassment complaint against Barnaby Joyce was compromised by political interference.

The review into Catherine Marriott’s complaint against the former deputy prime minister, which he denies, found the backgrounding of “political operatives” interfered with due process and ultimately led to the naming of the alleged victim.

“It is clear that the actions of the [WA parliamentary] members dealing with this matter further compromised the party and the victim,” the review by WA Nationals state director Simon Glassop says, according to Fairfax Media.

Ms Marriott lodged a complaint with the Nationals about Mr Joyce’s behaviour outside a beef industry event at Canberra’s Kurrajong Hotel in 2016.

According to Fairfax, the review of the investigation’s handling involved extensive contact between Nationals MPs and Ms Marriott and may have extended to “proof reading” her formal complaint.

It said it could have made MPs to look like “co-conspirators” in a push to bring down the party’s former leader.

Pages seen by Fairfax showed deep uncertainty within WA Nationals branch, after it formalised the complaint in February.

The move caused some Nationals to believe the complaint was “weaponised” to bring an end to the headlines on Mr Joyce’s affair with former staffer Vikki Campion.

State parliamentary leader Mia Davies’ decision to call for Mr Joyce to resign reportedly proved a critical factor in his decision to quit.

“It is clear that the actions of the (parliamentary) members dealing with this matter further compromised the party and the victim,” Fairfax reports the review document saying.

The backgrounding and informing (of) other political operatives interfered with the process and increased the risk of the knowledge of the allegation becoming public and ultimately the publicly (sic) naming of the victim.

“It deprived the federal leader the opportunity of a fair hearing.”

The review also reportedly found Ms Davies and fellow national MPs’ “public stand” in favour of Ms Marriott were “political” judgments designed to separate the WA Nationals from federal dysfunction.

“But it ultimately has placed our party firmly in the spotlight and has appeared to make us look like co-conspirators,” it read.

“The decision to meet and offer support and be in regular communication with the victim throughout the process, although well meaning, has led to more suspicion.”

In a statement to Fairfax, Mr Glossop said his report was prepared with a view to “developing a policy for dealing with serious matters such as a complaint against a politician or office bearer”.

He said it was a “confidential document for internal reference only”.

-with AAP