The District has sent erroneous notices to some Maryland residents, warning that they have failed to pay parking fines and may face further penalties, city officials said yesterday.

The errors have been traced to a recent batch of notices that were mailed to an estimated 20,000 Maryland residents.

But D.C. officials said they were uncertain how many of the notices actually contain mistakes.

"We really don't know what the problem was," said Robert Landolt, senior vice president for Datacom Systems Corp., the company that has a $500,000-a-year contract with the city to help collect parking fines.

He said the errors may have affected as few as a dozen notices.

The incorrect notices, which were prepared by Datacom, prompted a series of phone calls from Maryland residents Tuesday night to a talk show on Baltimore radio station WBAL.

"It just started snowballing," said executive producer Katherine McQuay, adding that she herself received a mistaken $50 warning.

A Maryland Motor Vehicle Administration spokesman said the inaccurate notices would not cause delays in renewing car registration.

Officials urged recipients to mail any erroneous notice to the address shown on the statement or to phone 293-4735, 393-6125 or 293-2220.