The Australian Federal Police (AFP) smashed on Tuesday what is believed as part of an international drug operation that led to the arrest of seven persons and the seizure of drug piles, with an estimated street value of $500 million.

AFP deputy commissioner Andrew Colvin told ABC that his agency's total haul last night was deemed as the biggest so far in history, with police disclosing that 306 kilograms of methamphetamine and 252 kilograms of heroin were confiscated in separate raids conducted in various Sydney locations.

The operation, Mr Colvin said, was backed by 11 months of careful planning, which also involved close coordination with the Australian Customs and Border Protection Service, and was set off by intelligence provided by the U.S. Drug Enforcement Agency (DEA).

Among those apprehended were four Hong Kong nationals and three Australian citizens, who Mr Colvin said were thought to be connected with drug syndicates based outside of the country.

All suspects, according to The Sydney Morning Herald, will face charges of "conspiracy to import methamphetamine and heroin and attempting to possess a commercial quantity of methamphetamine and heroin," before the Central Local Court in Sydney.

They were scheduled to appear before the court Tuesday morning, AFP said, and they face the prospect of spending the rest of their lives behind bars.

The suspects' arrest signalled that "these syndicate's operations now will be in disarray," Mr Colvin added.

Customs and Border Protection deputy chief Mike Pezzullo told ABC that the syndicate's operations were betrayed by their "brazen and unsophisticated concealment method."

The more than half-tonne of ice and heroin, Mr Pezzullo added, were discovered by probers in "terracotta pots concealed in bulk on palates within cardboard boxes and then shrink wrapped."

"Once we had a clear lead as to which containers to look at, it wasn't particularly difficult to find the gear inside those terracotta pots," he further explained.

Mr Colvin affirmed that "we detected with a high level of confidence that the terracotta pots contained narcotics."

The AFP chief offered too that due to high-level of information passed on by Australia's crime-busting partners "we had a reasonably good idea of when the consignment was coming in."

Government agents swooped down on targeted areas supported by eight search warrants served by authorities on different locations around Sydney, the AFP said.

Government figures revealed that more than 14 tonnes of illegal drugs were confiscated in the financial year 2011-2012, which the termed as its "most successful year in terms of drug seizures."

Evidently, the AFP is off to a good start with latest operation alone exceeding value of assets recovered by authorities in the past 12 months ending in June, placed by Mr Colvin at around $100 million.

"Countless lives would have been affected had this seizure made its way to Australian streets," the AFP chief added in a news brief held today at the national police agency's Sydney office.

Mr Colvin added that an investigation on the specific case remains underway, which could also take AFP agents on probes beyond the Australian border.

Also, he stressed that the success of AFP's operation today will not "compromise future prospects of arrests."

He expressed confidence that the AFP has vastly improved in coordinating its operations with partner agencies here and abroad, which should lead to future dismantling of criminal activities and more arrests.