Russian and Polish police have bust a counterfeiting operation in Poland, turning out "millions" of forged Deutsche mark banknotes, Interior Minister Viktor Yerin said Friday.


Yerin told a press conference that the plant had been discovered and liquidated two months ago as a result of the "close" cooperation between police squads of the two countries.


"This was a dangerous international crime group of counterfeiters who produced and put into circulation more than 2 million Deutsche marks ($1.3 million) in four European countries," Yerin said.


He said Russian and Polish police had started to suspect the existence of the crime group in September last year and now believed they had detained all the gang, with the assistance of Interpol.


The ministry's specialists say Deutsche marks and U.S. dollars are very hard to forge because they have plastic and metallic strips in them.


But police officials say counterfeiters use sophisticated equipment and the latest technology, including copying machines and devices similar to machines used by the government to print money.


Reuters reported that the latest development in the campaign against forgers was to incorporate kinegrams, pictures similar to holograms, that change according to the angle from which you look at them.