Police have busted an international drug syndicate that they allege has been using airline cabin crew on board flights from Malaysia to smuggle drugs into Australia over a number of years.

Key points: Investigators allege the drugs were carried on the bodies of cabin crew flying to Melbourne and Sydney

Investigators allege the drugs were carried on the bodies of cabin crew flying to Melbourne and Sydney Police seized luxury cars, $100,000 in cash and drugs during raids in Melbourne earlier this month

Police seized luxury cars, $100,000 in cash and drugs during raids in Melbourne earlier this month One of those alleged to have been involved in the syndicate told police he had made the trip to Australia 19 times before

The Australian Federal Police (AFP) and Victoria Police have arrested eight people in the past 10 days who they allege brought heroin, methamphetamine and cocaine worth $21 million into Australia.

Assistant Commissioner Tess Walsh from Victoria Police said the arrests occurred as part of Operation Sunrise, which involved the AFP, Australian Border Force and the Australian Criminal Intelligence Commission.

The joint investigative team has alleged that the syndicate used cabin crews at Malindo Air, a small airline based in Malaysia, to bring the drugs into the country.

Investigators allege the drugs were brought in via Melbourne and Sydney, carried on the bodies of the cabin crew.

One defendant allegedly told investigators it was his 20th trip into Australia.

"[Operation Sunrise] is a complex, five-month operation targeting an alleged Vietnamese organised crime syndicate based in Melbourne," Assistant Commissioner Walsh said.

Police seized heroin, methamphetamine and cocaine during raids earlier this month. ( ABC News: Karen Percy )

Assistant Commissioner Walsh said police believed the syndicate had been operating for at least five years and that the drugs seized so far were clearly "not the total amount of drugs" alleged to have been imported.

"This is a significant seizure but I think reality would say that it's not the total amount of drugs that this team have brought into this country," she said.

"Intelligence would tell us that this crew has been operating for some years, I would say five plus … I don't know whether or not it's decades."

Eight arrested across Melbourne

Those arrested by police include a 38-year-old woman arrested on January 7 in Tullamarine, and another six people arrested in raids at Sunshine North and inner-city Melbourne a day later.

On January 14, a woman from Richmond was also arrested.

Two of the defendants were Vietnamese-born Australians.

Six kilograms of heroin were seized, as well as 8kg of methamphetamine and half a kilo of cocaine.

Luxury cars, $100,000 in cash and drug paraphernalia were also seized.

Assistant Commissioner Walsh said the investigation was "active and ongoing".

Malindo Air's website describes it as a "premium airline with headquarters in Petaling Jaya", a town just outside of Kuala Lumpur.

In a statement, Malindo Air it was aware that one of its cabin crew had been arrested on arrival at Melbourne Airport on January 7.

While the airline said it had not had any "official communication" with its staff member or the AFP over the crew member's detention, the person had been suspended with immediate effect.

It said none of the other Malindo Air crew on the flight were detained.

"Malindo Air stands ready to co-operate with all the relevant authorities be it in Australia or in Malaysia in this regard," the airline said.

"Given all that we know to date and based on the findings of our internal investigations, we are confident that this arrest appears to be an isolated incident arising out of a crew's misconduct."