Suspicious behaviour near a grounded Sydney-bound flight in Johannesburg sparked a year-long investigation that culminated in 100 kilograms of cocaine being seized.

Five men were charged on Saturday over an alleged plot to import the drugs – which had an estimated street value of $40 million – in the cargo hold of a passenger plane.

Officers had been monitoring the group closely for the past year after receiving a report from an airline.

AFP Detective Superintendent Kristie Cressy said the arrival of the plane in Sydney on the weekend was the first time police had evidence of drug importation.

Two workers at Sydney International Airport, a 55-year-old Mascot man and a 61-year-old Coogee man, are alleged to have used their access to freight to facilitate the operation.

A 42-year-old Padstow man is alleged to have been the primary facilitator of the scheme, while a 62-year-old Hillsdale man allegedly co-ordinated the airport workers’ role in the plot.

Police say the two airport workers removed five large bags containing the cocaine from a container in the cargo hold of a Qantas aircraft that had recently arrived from South Africa on Saturday.

The alleged insiders then transferred the bags to a car driven by a 24-year-old Sydney man outside the terminal.

The three men were arrested shortly after the handover on Saturday afternoon, while two others were arrested later that evening.

They appeared at Parramatta Local Court on Sunday and will remain in custody until their next court appearance on November 30. The scheme’s alleged facilitator is due to make a bail application on Monday.

Each of the five bags found in the car contained bricks of a white substance wrapped in black plastic.

Forensic testing confirmed the substance was cocaine and each bag held about 20 kilograms.

It is estimated the haul could have been sold as 100,000 individual street deals.

The police investigation was sparked in October last year after an airline reported suspicious activity near the cargo area of a Sydney-bound flight in Johannesburg, South Africa.

Investigations in Australia identified the two airport workers as being in the vicinity of the flight when it arrived in Sydney and removed items from the cargo hold.

The airline that made the initial report provided significant assistance to police along with Sydney Airport and the Australian Border Force.

Cressy said people with trusted access in an airport precinct were critical to Australia’s tourism and trade sectors. But police would not hesitate to investigate and prosecute those who abused that trust to help organised crime, she said.

“The ultimate motivation for assisting organised criminal groups is greed, so [the workers] were going to be recipients of a cash reward,” she said on Monday.

“Trusted insiders and people with relevant access are approached by organised crime groups to facilitate the importation of drugs into our country.

“The access that is required is of interest to organised crime groups and that’s precisely what the AFP and its partners are interested in investigating.”

Australian officers in South Africa are continuing investigations with local authorities.

– AAP