Scotland Yard has seized a record number of counterfeit coins in raids on three properties just outside of London, the force announced Thursday. Three suspects have been arrested in the case.

Police said in a statement that they had recovered more than 4 million pounds ($6.3 million) worth of blank coinage from a 40-foot- (12-meter-) long shipping container during Wednesday's swoop. About 100,000 pounds worth of fully-pressed counterfeit currency was discovered at the properties in question and in two vehicles in rural areas outside the British capital.

The statement said the seizure was thought to be the biggest-ever haul of bogus coins in Britain.

A police spokesman said the fakes were one-pound coins — a weighty, yellow-colored currency which has been in circulation since 1983 and is popular with counterfeiters. Britain's Royal Mint has warned of an increase in the number of fake one-pound coins in circulation, with the most recent survey putting counterfeit rates at about 3 percent.

Police said three men, ages 52, 43 and 27, had been arrested in connection with the find. Authorities are still hunting for the press that made the fakes.