The NSW corruption watchdog in New South Wales has made its most significant findings yet against former New South Wales Labour Party power broker Eddie Obeid.

In its latest finding, the Independent Commission Against Corruption has alleged that Obeid engaged in serious corrupt conduct by promoting his own interests to a range of ministers in relation to a contact to purchase, supply and operate water infrastructure in the North-West Growth Centre in north-western Sydney.

Serious corruption findings were also made against former NSW infrastructure minister Anthony Kelly, his former chief of staff and Gilbert Brown and former minister Joe Tripodi.

The investigation came about following a complaint made to the Commission in 2012 which concerned the possible acquisition by Obeid family interests of a company known as Australian Water Holdings (AWH) in return for Eddie Obeid using his political influence within the NSW Labour Government of the time in order to further the interests of that company.

It found that Eddie Obeid’s son, Eddie Obeid Jr, was working for an AWH-related company known as Australian Water from around 2007.

By that time, it alleges that Eddie Obeid Sr was aware of his son’s involvement with AWH and was also aware that AWH wanted to proceed with a PPP proposal for the purchase, supply and operation of water infrastructure in the North-West Growth Centre in north-western Sydney.

Obeid also knew, ICAC alleges, that his son was interested in acquiring shares in AWH and that by July 2008, the Obeid family had acquired shares in that company.

Knowing this, it says that Obeid then used his position to promote AWH’s case to a number of ministers and premiers.

“The Commission is satisfied that Edward Obeid Sr used his position as a member of Parliament to promote AWH’s interests to a number of ministers and premiers at a time when he knew that his family or a family entity could benefit if they acquired shares in the company and the PPP proposal proceeded,” ICAC said in a statement.

ICAC also made corruption findings against Kelly and Gilbert over their respective roles in the misrepresentation of the value of the AWH proposal to the Cabinet Standing Committee on the Budget in 2010, with the intention of improperly favouring Obeid.

An initial draft Cabinet minute prepared by Department of Premier and Cabinet associate director of investment and economic development Brian McGlynn had recommended that the ASW PPP proposal be rejected on several grounds.

These include that it did not deliver value for money to either Sydney Water or the community and that it did not transfer sufficient levels of risk to AWH.

Having had this forwarded to his office (with the intention that it would be on-forwarded to the Budget Committee of Cabinet), ICAC found that Brown instead helped to draft a new minute which was favourable to the proposal proceeding.

Kelly, too, engaged in serious corrupt conduct by misusing his office as a minister with the intention of improperly favouring Obeid by arranging for the new minute to be prepared and submitted whilst Tripoli did likewise by using his position as a member of Parliament to prepare a draft Cabinet minute which would be used by Brown and Kelly as the basis for that minute, ICAC said.

The above was done, ICAC found, in order to improperly favour Obeid by enabling AWH to proceed to direct negotiation with the NSW Government concerning its proposal.

It recommended charges be laid against Obeid, Brown, Kelly and Tripodi.

“The Commission is of the opinion that consideration should be given to obtaining the advice of the Director of Public Prosecutions with respect to the prosecution of Edward Obeid Sr, Mr Kelly, Mr Brown and Mr Tripodi for common law criminal offences of misconduct in public office,” it said.

The charges are the latest against Obeid, who is already serving a maximum five-year prison sentence over secret business dealings in relation to commercial leases as Circular Quay.

The Criminal Court of Appeal is considering an appeal against that conviction and sentence.

Obeid and his middle son Moses also face charges over an alleged $30 million coal deal involving the family’s rural property near Mudgee.

No adverse findings were made against a string of other witnesses.