SEATTLE — Staff at the Port of Seattle steered contracts to preferred bidders and committed several other instances of fraud, a former federal prosecutor found in a report released Wednesday.

Former U.S. Attorney Mike McKay was hired by the port early this year to look into its contracting practices, following an state audit that found them lax and vulnerable to fraud.

In a 57-page report, McKay said his team’s $1.4 million, 10-month investigation did not uncover instances of embezzlement or personal gain by port employees. But it did find 10 instances of fraud, including a port employee’s decision to provide a potential bidder with internal cost estimates for the third runway at Seattle-Tacoma International Airport.

However, McKay’s report also deemed a key finding of the state audit — that the port wasted more than $90 million — to be unsubstantiated. The contract at issue in that finding was handled properly, he said.

The investigation also “exposed a culture that tolerated suppressing information” from the port’s elected commissioners, two of those commissioners wrote in summarizing the report.

Port Chief Executive Tay Yoshitani said he was “deeply disappointed and saddened” by the fraud findings and would immediately begin implementing McKay’s recommendations, which include better documentation and more involvement by the port’s legal department.

“Any staff member who has committed fraud will be appropriately disciplined and potentially terminated,” Yoshitani said in a written statement.

Much of the fraud McKay cited concerned the construction of the Sea-Tac airport third runway, which opened last month. A port employee gave a potential bidder for a major part of the project, TTI Constructors, an internal estimate.

“We conclude that providing an internal port estimate to only one bidder without notification to the public or any other prospective bidders was an act of extremely poor judgment,” the report found.

Furthermore, when TTI did submit a bid of $125 million for the work, former port CEO Mic Dinsmore and another employee made cosmetic changes that made the bid appear cheaper than it was.

McKay also found that Dinsmore clearly broke ethics rules, but did not commit fraud, in obtaining an internship for his daughter at the port’s lobbying firm.

The U.S. attorney’s office in Seattle launched its own investigation following the state auditor’s report. That investigation is ongoing.