Counterfeit US currency seized by the US Secret Service and Peruvian police, November 15, 2016. US Secret Service

US and Peruvian agents seized a record $30 million in counterfeit dollars in the biggest haul of fake US cash ever by the US Secret Service, the agency said on Thursday.

The operation was the result of a worldwide investigation focused on six criminal organizations based in Peru, which is the world's largest maker and distributor of counterfeit US money.

The stash was discovered on November 15, when more than 1,500 Peruvian police, along with Secret Service agents, carried out 54 search warrants in a pre-dawn operation that led to the arrest of 48 people in Lima, the agency said in a statement.

Fifty thousand fake euros were also seized and 48 people arrested in the raids, called Operation Sunset. Six counterfeit plants were shut down, eight counterfeit-manufacturing presses were seized, and more than 1,600 printing plates and negatives of different denominations were found, the Secret Service said.

"The Peruvian government has become a valuable partner in our efforts to combat counterfeit currency," Joseph Clancy, the director of the Secret Service, said in a statement. "Protecting the nation's financial infrastructure is a vital component of our integrated mission of protection and investigations."

Counterfeit US currency seized by the US Secret Service and Peruvian police, November 15, 2016. US Secret Service

The agency, which is best known for protecting the US president and visiting foreign dignitaries, was originally founded to combat currency counterfeiting. It opened an office in Lima to fight widespread counterfeit activity in the country and support the Peruvian National Police.

The two countries have created an anti-Counterfeiting Task Force and Peruvian police officers have received training from the Secret Service.

Corruption and crime have become high-profile concerns in Peru. In 2014, Peru was the world's second-largest producer of coca, the plant from which cocaine is made, behind Colombia and ahead of Bolivia, both of which it borders.

Criminal groups have sprung up in Peru to direct the flow of drugs out of the country.

Peru's Interior Minister Daniel Urresti speaks to media next to seized cocaine bricks at a police headquarters in Lima, November 4, 2014. REUTERS/Enrique Castro-Mendivil

Those criminal organizations are believed to have infiltrated public institutions, bribing legislators and security officials. The belief that such rot is becoming widespread has led some to declare Peru is slipping toward being a "narco state."

Cocaine is thought to flow eastward into Bolivia and Brazil, out from the country's Pacific ports, or through the country's airports to points around the globe.

Illegal drug flights are also a common transport method, and the Peruvian government recently reinstated a controversial policy allowing for the shoot-down of planes suspected of carrying drugs.

Peru has largely avoided the violence seen in places like Colombia and Mexico, but Peruvian criminal groups are responsible for some bloodshed, and their suspected ambitions to grow may bring more.

(Reporting for Reuters by Ian Simpson; editing by Richard Chang)