The other defendants include senior executives of two subcontractors and operators of a supplier for the airport’s much publicised third runway project.

They were released on bail and are expected to appear at Eastern Magistrates’ Courts on Friday.

The alleged offences took place between January 2017 and August 2022.

Yin and Lee were first employed by the authority as engineers on short-term contracts to help in managing and supervising works for the third runway project. Yin was promoted to general manager in October 2018 and Lee to principal manager in May 2022.

Yin allegedly took HK$1 million in bribes from two senior executives of a steelworks subcontractor to help it secure a contract for the supply and installation of platforms for the main reclamation works of the project. The contract sum amounted to more than HK$37 million, according to the ICAC.

Lee, meanwhile, had allegedly conspired with an owner of a filling materials supplier to assist it in securing subcontracts for the reclamation and other works for the new runway, pocketing HK$2.5 million in bribes in the process.

The related subcontracts were worth HK$28 million.

He also allegedly accepted bribes of HK$800,000 for helping a sand supplier to secure orders worth more than HK$140 million.

Lee and his wife were also alleged to have laundered the crime proceeds of about HK$6 million, which included the bribes.

ICAC operations department chief investigator Matthew Chang Chor-ming on Wednesday said that the investigation was still under way and he would not rule out further arrests or prosecutions.

The ICAC investigation was prompted by a corruption complaint filed about a year ago. In an operation last August, code-named Blizzard, ICAC officers arrested 30 people, including Yin, Lee, and two other senior officials of the Airport Authority.

Chang said: “The ICAC attaches much importance to the case as it involves huge public interest. The investigation concerned mainly the awarding of works and supplies contracts, as well as administrative and financial matters.

“Our investigation revealed no issue involving the quality of the works or specifications of the materials.”

He also added that the investigation did not find the defendants were part of a syndicate.

The scale of the three-runway system project was almost equal to building a new airport next to the existing one on Chek Lap Kok, according to the authority.

The HK$141.5 billion project involves seven core projects, including reclaiming 650 hectares of land, building a new 3.8km long runway and supporting taxi systems, as well as expanding Terminal 2. It also boasts a new 2.6km-long automated people mover and a new baggage handling system capable of processing 9,600 bags an hour.

Construction started in 2016 and the new runway had its official unveiling last November. It is expected to be in full service after the completion of the Terminal 2 expansion works which is scheduled for 2024.

The authority funds the project by using its operating surplus, levying an airport construction fee on departing passengers, and borrowing from the market through bank loans and bonds.

The authority has not said it expected delays or budgets to be exceeded for the project at this stage.

Lawmaker Gary Chan Hak-kan, chairman of the Legco security panel, expressed concerns about anti-corruption work in the authority.

“The arrest of 30 people shows that there is much room for improvement in the cooperation between the ICAC and the Airport Authority in terms of anti-corruption work,” Chan said.

He urged the ICAC to tailor-make certain anti-corruption measures for the authority and also step up education and publicity towards contractors and their staff.

Meanwhile, the authority said it had reviewed the relevant documents and records to check the safety and quality of the works carried out by the subcontractors in question.

“[The authority] concluded that all concerned works complied with the statutory and [authority] requirements, with no abnormalities and deficiencies identified,” it said in a statement.

It also confirmed that it had terminated the employment contracts of all former staff involved in the ICAC operation.

But it declined to comment further. “It is inappropriate for [the authority] to comment on ongoing law enforcement actions. [The authority] will continue to provide assistance upon request by the law enforcement agency,” the statement said.