Four Romanians have been charged with hacking into the computer systems of hundreds of US merchants and making millions of dollars in purchases with stolen credit card data, the Justice Department said Thursday.

The department identified the four as Adrian-Tiberiu Oprea, 27, of Constanta, Romania, Iulian Dolan, 27, of Craiova, Romania, Cezar Iulian Butu, 26, of Ploiesti, Romania, and Florin Radu, 23, of Rimnicu Vilcea, Romania.

Oprea was arrested in Romania last week and Dolan and Butu were arrested after arriving in the United States in August, officials said in a statement. Radu is at large.

An indictment filed with a court in New Hampshire charges the four with conspiracy to commit computer fraud, wire fraud and access device fraud.

According to the indictment, they hacked into the computer systems of more than 200 US-based merchants between 2008 and May 2011, stealing credit, debit and gift card numbers.

"Members of the conspiracy have compromised the credit card data of more than 80,000 customers, and millions of dollars of unauthorized purchases have been made using the compromised data," the Justice Department said.

The four face a maximum of five years in prison for computer fraud, 30 years in prison for wire fraud and five years in prison for access device fraud.