Two of the NSW Premier Dominic Perrottet's brothers have been summonsed to give evidence at a state parliamentary inquiry into the Hills Shire Council in Sydney's north-west.
A parliamentary Upper House committee has summonsed Hills Shire Councillor Virginia Ellis and Christian Ellis as well as Charles and Jean-Claude Perrottet, after they failed to respond to invitations to give evidence.
The inquiry, which will sit for two days next week, is looking into allegations of impropriety by members of the council in Sydney's north-west and property developers in the area.
The committee said in a statement the four people summonsed were key individuals who "could assist the committee with its questions in relation to Hills Shire Council".
Premier Perrottet said he had not spoken to his brothers about being summonsed.
"No I haven't, not at all, it's a matter for the Upper House — I'm not going into those details," he said.
Committee member and Upper House deputy leader, John Graham, said the committee had issued the summons' after the witnesses failed to respond to invitations to face the inquiry.
"The committee is now seeking the co-operation of witnesses who may have some light to shed on the suggestions that have been made, but have found it very hard to get them to agree to give evidence," he said.
"As a result, we have taken the serious step of issuing summons and we're hoping there is co-operation with the work of the committee."
Committee chair Sue Higginson said some individuals continued to ignore the committee's correspondence and appeared to be deliberately avoiding accepting service of the summons.
"This appears to be a calculated and coordinated attempt to avoid scrutiny," she said.
"The committee is extremely concerned by this behaviour and calls on these individuals to cooperate with the inquiry."
In June, Liberal MP Ray Williams alleged, under parliamentary privilege, that senior members of his party and state executive, and a former Hills councillor received payment from Sydney property developer Jean Nassif.
The veteran MP claimed the payments were designed to garner support for a proposed development around the Cherrybrook Metro station.
In parliament, Mr Williams went on to suggest that existing members of the local council had then been replaced with others who would be more amenable to Mr Nassif's proposal.
All allegations have been denied by Mr Nassif.
Mr Nassif's company Toplace has been the subject of numerous complaints regarding building defects in its developments.
The company has previously said it stands by its projects and has always fixed any defects where they have occurred.
Mr Nassif has declined to appear before the inquiry ahead of the state election, saying he will be in a remote part of Lebanon at the time.
In a letter to the inquiry, Mr Nassif said he does not intend to return to Australia before March, asking that the hearing be postponed "if my evidence is needed".
But Mr Graham said the inquiry would have to work quickly to finalise matters before the state election.
He said he can see no reason why Mr Nassif could not give evidence from Lebanon.
"I can't see any obstacle to him being able to give evidence say by video link, and that would be a welcome development because it allows us to get to the bottom of what happened," he said.
