Premier Dominic Perrottet said he had referred the claims made in parliament last week to ICAC after receiving advice from his department.

Castle Hill MP Ray Williams alleged his party, the Liberals, had members who engaged in undemocratic behaviour last year when existing party councillors for The Hills Council in Sydney were replaced.

Specifically he cited Christian Ellis, who sought to challenge Ms Ley before May's federal election prior to then prime minister Scott Morrison intervening to maintain her as the party's Farrer candidate.

Mr Williams alleged that Toplace, a developer with ties to Mr Ellis, had paid significant sums to him and Liberal Party members to arrange new councillors who would be supportive of its future building applications.

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