Madrid (CNN) -- Spanish police have arrested 750 people after a nationwide investigation into fake businesses, according to a statement Wednesday.
The mass arrests were part of a crackdown on a scam through which $28 million of public funds were paid out for Social Security benefits, according to the police statement.
Police targeted fake companies operating in tourism, construction, industrial cleaning and package delivery, and made the arrests over recent months.
"Among those arrested are 30 managers of the fake companies who, without any real business activity, registered people for Social Security to illicitly obtain benefits, or to obtain residency or working permits for foreign citizens," the police statement said.
A total of 8,400 people were registered on Social Security rolls as part of the scam, and in 2,100 cases, they received some form of government payout. In addition, 362 foreigners were able to get working or residency papers in Spain through the fraud, the police said.
The investigation uncovered 4,000 crimes of document and other fraud linked to the payments from public funds.
More than half of the 750 arrests were made in Madrid and Barcelona, but there were also dozens of arrests each in the cities of Almeria, Alicante, Jaen, Granada, Valencia and Guadalajara.
The operation, which the police said was the largest to date, represents about half the arrests made in the past year to crackdown on such fraud. Police say it has cost the state a total of $64 million. The police statement did not detail how they would recover the money or revoke fraudulent working papers.
The Labor Ministry press office said the 8,400 people falsely added to social security rolls were recorded as part of the government's employment statistics. But they are likely to have had little impact on the real statistics, which show 5.9 million Spaniards out of work and the unemployment rate at 25.9%.