Police have charged two Polish men in connection with the seizure of 1.2 tons of drugs in Sydney — the biggest haul in the country this year.

The Australian Federal Police (AFP) seized the massive haul of MDMA, the equivalent of about 4 million tablets, during a raid on a storage facility in Hornsby, in Sydney's north. It was the largest drug haul for 2016, and the fourth largest MDMA haul in Australian history, ABC News reported.

The drugs, with an estimated street value of $145 million, were discovered in Sydney after a tip-off. Two Polish nationals, aged 28 and 29, were arrested and have since been charged over the haul.

Border Force Commander Tim Fitzgerald said the drugs came from the Czech Republic and the syndicate went to extreme lengths to conceal them.