(CNN) - Mitt Romney's presidential campaign complained Saturday of telephone calls to some North Dakota residents that falsely claim to be paid for by the Romney campaign.
In a letter to North Dakota's attorney general seeking an investigation, lawyers for the Massachusetts Republican say they have heard reports of calls that are either automated or live and falsely direct North Dakotans to volunteer for Romney. Some also begin mid sentence and/or end with the caller laughing.
"Clearly our campaign is not responsible for such prank telephone calls," the letter stated.
The letter also said the campaign has connected some of the calls to an organization that is supporting John McCain. A McCain spokesman denied the campaign is connected to the calls, calling the notion "absurd."
- CNN's Peter Hamby contributed to this report