The United States has moved against what it describes as a major international money laundering network which has operations based in Ireland.

The PacNet group, a Canadian international payments processor, was allegedly clearing money based on scams targetting elderly and vulnerable victims involving fake lottery wins, sweepstakes and letters from psychics.

The US Treasury Department claims that the PacNet Group - with addresses in Co Clare, Canada and the UK, and subsidiaries in 15 other countries around the world including Hong Kong, Mumbai and Johannesburg - has "a lengthy history of money laundering".

The US has also taken action against 12 individuals involved with the group - five of whom have Irish addresses.

According to court documents made available today, PacNet has been operating for 20 years and in the last year alone processed payments for more than 100 different postal fraud campaigns, totalling tens of millions of dollars.

In a joint operation the US Department of Treasury, Department of Justice and the US Postal Inspection Service designated the PacNet Group a transnational criminal organisation.

The legal papers show seven PacNet Group companies with addresses in Shannon, Co Clare.

The individuals named are all directors or high-level executives and the five people with Irish addresses are all in either Co Clare or Co Limerick.

The US authorities claim that PacNet was "knowingly processing payments on behalf of a wide range of mail fraud schemes that target victims in the United States and throughout the world".

These scams were mostly based around letters to people about bogus sweepstakes, false lottery wins, and psychic visions of windfalls from a fortune teller named Maria Duval.

Their investigations revealed that in a typical scenario, scammers would post fraudulent letters to victims telling them about some cash windfall they are due to receive from a lottery or inheritance or other bonus in a country in another continent, and if they just send some money in, they will receive the details.

The fraudsters then arranged for their victims to send their cash and cheques directly to one of PacNet's companies.

PacNet then deducted its fees and commissions and passed the rest of the money onto the con artist either by wire transfer or by making a payment on the scammer's behalf.

The US authorities have also moved against multiple "direct mail" scam artists, and those who enabled them to carry out their cons, including a printer based in India who prints and ships the letters, and brokers who buy and sell lists of victims who've already fallen for other scams.

All property and other assets in the US of the 12 PacNet individuals have been frozen, and people or entities in the US are prohibited from engaging in transactions with them.

According to the US Treasury, the methods used by the PacNet payment processing operation made it difficult for financial institutions to detect the scam and suspicious activity.

The US Treasury Department also says that two of the PacNet directors were involved in couriering cash on behalf of clients. One is listed as the chief pilot for moving bulk cash, and another allegedly instructed his employees to mislabel customs forms to "evade cross-border reporting requirements".

In 2002, two of PacNet's corporate entities in Canada and Ireland acknowledged in court proceedings that various dealings were breaking US law.

Two executives promised the court in Washington State on that occasion that they would not use postal services to process illegal lottery payments.

The Department of Treasury also said there had been interactions in 2009 and 2014 between US legal authorities and PacNet.

RTÉ News has contacted PacNet Services in relation to the US authorities' charges but the company has not yet issued any comment.