Germany and Belgium have seized 23 tonnes of cocaine in the biggest-ever haul of the drug in Europe, German customs said Wednesday.

"The enormous amount of cocaine would have brought in several billion euros (dollars) in street sales," the customs office said in a statement.

German officers had discovered 16 tonnes of cocaine hidden in containers from Paraguay at the port of Hamburg on Feb. 12.

Joint investigations into the stash with Dutch officers led authorities to swoop on another 7.2 tonnes in cocaine at the port of Antwerp in Belgium, German customs said.

A 28-year-old man was arrested on Tuesday in the Netherlands in connection with both the German and Dutch hauls totaling 23 tonnes, it added.

Customs officers at the busy port in Hamburg had decided to take a closer look at the Paraguayan containers after noticing "clear irregularities" with its contents – tin cans that were meant to be filled with putty.

"Beyond a layer of genuine goods packed just behind the container door, numerous tin cans were in fact filled with other goods," said customs.

Investigators ordered the containers unloaded, and found the cocaine stash in over 1,700 tin cans.

"This is the largest amount of cocaine ever seized in Europe and one of the largest single seizures worldwide," German customs said, referring to the Hamburg haul.

In all, 102 tonnes of cocaine headed for the European continent were intercepted last year by an international law enforcement project co-implemented by the United Nations.