Allegations levelled by a Liberal MP against his own party in parliament have been referred to NSW’s corruption watchdog.

Castle Hill MP Ray Williams has alleged the former mayor and six Liberal councillors in The Hills Shire Council were replaced by Liberal Party state executive at the council elections “without the usual pre-selections processes normally afforded to such positions”.

He made the accusations in the NSW state parliament under parliamentary privilege last night.

He said the previous mayor and former councillors were held in “extremely high regard” and their removal came as a shock to the community, while the party’s executive endorsed new candidates.

“Allegations have been raised with me that senior people within the NSW Liberal Party, a member of the Liberal Party state executive and former Hills councillor were supported financially at the time by a large developer by the name of Jean Nassif, who owns Toplace,” Mr Williams told parliament on Thursday evening, according to Hansard.

“Apparently prior to the council elections, Jean Nassif of Toplace, met with Christan Ellis and other senior members of the Liberal Party who were paid significant funds in order to arrange to put new councillors on The Hills Shire Council who would be supportive of future Toplace development applications.”

Mr Williams has called for an external investigation.

Premier Dominic Perrottet later confirmed to Ray Hadley he had referred the matter to Independent Commission Against Corruption (ICAC).

“Following advice from the [Department of Premier and Cabinet] I have referred the matters raised under parliamentary privilege last night to the ICAC.”

Press PLAY below to hear Ray explain the allegations