Tony Nutt, the NSW Liberal Party director, has taken the extraordinary step of authorising Mick Symons, the former director of investigations at the Independent Commission Against Corruption, to investigate allegations of serious misconduct at two party branches.

Mr Symons has shown up at party members' homes unannounced and asked them to produce phone records and tape-recorded interviews, members of the Homebush North branch and Manly Young Liberals say.

Allegations said to have led to suspension of the branches include members impersonating others at teleconference meetings, renewing other people's memberships without their knowledge, enrolling to vote at false addresses, and branch stacking.

Documents obtained by Fairfax under freedom-of-information laws show a third branch, the Wentworthville Young Liberals, has been fighting party headquarters' move to suspend it over claims of "harassment" and "intimidation" in an expensive long-running Supreme Court challenge.

The branch has challenged party headquarters to prove claims by a member that he was "intimidated" into not running for branch president. The party is vigorously defending the case and has retained a QC and the high-priced Swaab Attorneys. The Liberals' legal bills are already understood to top $80,000.

All three branches are controlled by the party's right wing, whose members claim investigations are being ordered selectively by the ascendant "centre-right" and "left" factions that control the party's all-powerful state executive.

Mr Symons said: "I cannot discuss any aspects of my duties with the Liberal Party."  Mr Nutt declined to comment.

The Liberals announced the hiring of Mr Symons in May, as a "governance" consultant. The true scope of his role as not been known until now.

One member of the party's centre-right faction said wrangling over the Manly branch was particularly intense because its control would influence future preselection votes for seats held by NSW Premier Mike Baird and Prime Minister Tony Abbott.

Branches in those seats are particularly prized, the source said, because their incumbents are viewed as likely to step down from Parliament when their leadership ends.

"The president [of the Manly branch], aligned with the centre, went to the right," the party member said. "[The] two losing sides called foul. There's no way they're going to give a branch away to an opposing faction. It's life and death."

Young Liberal branches have the same voting rights as any other in influencing party preselections.

The dispute over Wentworthville has been quietly playing out through the Supreme Court since February, when the party announced it would suspend and dissolve the branch. The party reversed that decision months after litigation was started, but the case continues.

The right faction claims the branch has been suspended as part of a finely balanced factional fight between the right and the centre in the western suburbs.

Some on the right view the branch's delegates as potentially decisive in voting for future federal and state candidates for Parramatta and Granville.

"It's the Deathstar," one local party factional activist said of the branch's perceived importance.

The party's hard-right faction has been decimated and outmanoeuvred in recent years. It controls only two positions on the party's 21-member state executive.

Do you know more? jrobertson@smh.com.au