All of the five, four men and one woman, were released unharmed and they were meeting with embassy officials, Tamaulipas state attorney general Jose Herrera said in an interview with a local radio.

The abductions happened on July 14 when they were driving in Reynosa, across the border from McAllen, Texas in the United States by an alleged human trafficking group, Herrera said.

Their captors had phoned the South Korean diplomatic mission in Mexico, demanding 30,000 U.S. dollars in ransom from their families, said the state attorney general.

Police tracked several phone calls before finding the hostages in a hotel in Reynosa, he said.

Herrera said the five South Koreans were actually in Mexico looking to enter the United States illegally.

"It seems the people smugglers offered to take them across to the United States but then kidnapped them for a much bigger ransom," said a spokesman for the Tamaulipas state attorney general's office.