SYDNEY (Reuters) - Australian Federal Police said on Saturday they had arrested two Polish men in connection with the seizure of 1.2 tonnes of crystal MDMA, the main chemical used in ecstasy pills.

A raid on a storage facility in Sydney’s north on Thursday uncovered the drugs - Australia’s largest seizure this year - in a consignment of aluminum rollers imported from the Czech Republic, police said.

The haul equates to more than 4.1 million ecstasy tablets, with an estimated street value of A$145 million ($109.95 million).

“Not only is it the largest drug seizure we’ve seen in 2016, it’s the fourth-largest MDMA haul in Australian history,” AFP Deputy Commissioner of Operations Justine Saunders said at press conference.

Two Polish men, aged 28 and 29, were arrested on Friday and charged with serious drug importation offences. They could face life in prison if found guilty.

Investigations by police and Australian customs are continuing and further arrests are anticipated, Saunders said.

Tim Fitzgerald, a regional commander at the Australian Border Force, said the syndicate involved had used a very sophisticated technique to hide the drugs.