Former NSW energy minister Chris Hartcher and MPs Chris Spence and Darren Webber have voluntarily withdrawn from the Liberal Party while a corruption probe against them is carried out.

The Independent Commission Against Corruption (ICAC) is examining allegations the central coast MPs corruptly solicited and concealed prohibited political donations in return for favours to those who made the payments.

The ICAC announced on Tuesday it would hold a public hearing into the allegations starting on April 28.

In a statement on Wednesday the Liberal Party’s acting state director Simon McInnes said the three MPs had “voluntarily withdrawn” from the party until the ICAC proceedings are determined.

It’s believed the party had already started suspension proceedings against the three MPs, who have only just nominated for pre-selection for their Central Coast seats.

Those being examined by ICAC for alleged corrupt dealings include the three MPs along with Timothy Koelma and Raymond Carter.

It’s been alleged that staff members of Mr Hartcher funnelled illegal political donations, including from prohibited donors, through a front company before the 2011 election.

The corruption watchdog is also examining whether Mr Hartcher favoured the interests of the private company Australian Water Holdings after it allegedly made payments to Eightbyfive, a company set up by his staffer Mr Koelma.