The six men were arrested in a hotel room near Vienna airport as they tried to pass off five Picasso paintings for 50 million euros ($55 million), police said.
The buyer was in fact a police officer in disguise. Police commandos arrested the five Austrians and one Slovenian "in case they were armed," a statement said.
Subsequent raids in homes and cars found 14 fakes complete with forged artists' signatures and counterfeit certificates of authenticity signed by Picasso's son.
The arrests took place earlier this year but were only announced on Monday. The men, now on bail, said they believed the works were genuine, police said.