MDMA worth £44million has been found hidden in a digger being shipped from the UK to Australia.
In total five people were arrested after police seized more than 450 kilograms of the class A drug while it was being transported from Southampton to Brisbane on 15 March.
Danny Brown, 53, and Stefan Baldauf, 60, were arrested in Putney by National Crime Agency (NCA) officers on 15 June, while Peter Murray, 57, was held outside his home in Greenwich on 1 October.
All three have been charged with conspiring to export Class A drugs, while German national Baldauf was also charged with illegal entry in breach of a deportation order. The men are due to appear at Kingston Crown Court on 15 January next year.
Australian Federal Police (AFP) arrested two men, aged 33 and 42, in Sydney, who have also been charged.
Australian Border Force officers found the hidden drugs when an X-ray revealed the anomalies in the excavator.
The arm - or boom as it is known - of the digger had been lined with lead in a bid to mask the 226 packages of MDMA.
After being emptied, the excavator was delivered to its intended recipient in Sydney to identify other suspects planning to pick up the machinery, police said.
NCA investigators from the UK discovered the conspiracy in encrypted messages collected as part of an investigation into the communication networks of criminal gangs.
They uncovered the plan hatched by a London-based crime group to import drugs into the UK, then export the narcotics to Australian heavy plant machinery.
Encrypted messages sent on EncroChat devices between January and June this year set out plans to buy the excavator in the UK along with hand-drawn illustrations of the concealment inside the arm, police said.
Officers also found details of the costs relating to the importation and confirmation that the machinery had been loaded onto a vessel in Southampton on 24 January and arrived in Brisbane seven weeks later, the NCA said.
Chris Hill, senior investigating officer for the National Crime Agency, said this amount of MDMA could have made the suspects nearly £18 million in the UK and in Australia the profits could have been even higher at $79 million (£44m).