A Sydney engineer with links to a former prime minister says the NSW premier’s brother approached him for a $50,000 donation in a bid to unseat a federal MP.

Businessman Frits Mare has told a NSW parliamentary inquiry Jean-Claude Perrottet, along with Hills Shire Councillor Christian Ellis, asked for a $50,000 contribution from him in 2019 to “get rid of (Liberal MP) Alex Hawke, stack his seat”.

“They told me they wanted to unseat a sitting member of parliament, the federal member in the seat of Mitchell (northwest Sydney),” he told the inquiry on Wednesday.

“They were raising money for that and they thought I’d be a prime candidate to contribute to that.

“They said because I was friendly with a previous prime minister who got unseated and that Alex Hawke was one of the people who had the numbers to unseat him … therefore they thought I should help revenge that.

Mr Mare told the inquiry Mr Hawke was a staunch supporter of then prime minister Scott Morrison and suggested he may want to avenge Mr Hawke’s role in the ousting of Tony Abbott as Liberal Party leader.

“At that point I terminated the conversation … I wasn’t interested.”

“The member, whatever I think of him, was elected by voters and it’s up to them unseat him, not me,” Mr Mare said.

Mr Perrottet, the 26-year-old brother of NSW Premier Dominic Perrottet, was among several Liberal-aligned witnesses summonsed to appear before the inquiry.

The probe is examining matters raised under parliamentary privilege by Liberal MP Ray Williams in June, alleging several senior members of his party were paid to install new councillors who would be friendly to Sydney developer Jean Nassif.

When asked about the inquiry, the premier said it was an attempt by Labor to “throw political mud in an election campaign”.

“The advice I’ve received is that it (the allegations by Mr Williams) went to the ICAC (Independent Commission against Corruption) and no further investigation needed to be undertaken,” he told reporters.

Nationals MP Scott Barrett, who sits on the committee, said the scope of the inquiry was veering away from the original allegations raised by Mr Williams.

But Labor MPs John Graham and Penny Sharpe argued that “there could be overlap” since the seat of Mitchell encompasses the Hills Shire in northwest Sydney.

Councillor Virginia Ellis, Christian Ellis and Jean-Claude Perrottet, the NSW Young Liberals’ secretary, were among witnesses summonsed to appear on Wednesday and Thursday but failed to show up.

“I cannot overstate what a serious matter this is, but also that it’s unprecedented,” Ms Sharpe told reporters after the hearing.

“We’re now in the situation where the committee has hired professional process servers to try and have these people who so far have been evading the summons to turn up”.

Greens MP Sue Higginson said parliamentary staff had “made multiple attempts to personally serve the summons on these individuals but have been unsuccessful”.

Ms Ellis and Jean-Claude Perrottet have been contacted for comment.

Another of the premier’s brothers, BP manager Charles Perrottet, was also summonsed but might not be in NSW.

The inquiry resumes on Thursday with another hearing slated for next week.

– AAP