The NSW Attorney-General has applied to have a Sydney man declared a vexatious litigant after he launched numerous and repeated court actions against several neighbours, including over a Facebook post, leaving them with tens of thousands of dollars in legal bills.

Gabrielle Upton will ask the NSW Supreme Court on June 7 to stay all or part of any legal proceedings brought by Nader Mohareb​ and prohibit him from starting any new cases without the court's permission.

Nader Mohareb says he has been pestered by neighbours on Scotland Island for three years. Credit:Facebook

The drastic move comes after Mr Mohareb recently began a third attempt to prosecute his Scotland Island neighbour Matthew Palmer​ for perjury, despite the District Court twice dismissing the case, a decision upheld by the Court of Appeal. Mr Mohareb has since added a claim for assault following an alleged altercation in a car park, which he filmed on his mobile phone.

Mr Mohareb has also filed a claim in the District Court against the island's water taxi driver Alexander "Alex" Kelso for defamation and trespass. And he is attempting to sue Church Point ferry driver Taylor Booth for trespass.