Drivers face a crackdown on illegal number plates.

Transport Control Department traffic officers will carry out “routine checks to ensure motorists are in compliance with the regulations”.

TCD issued the warning after an increase in the number of plates that do not conform with the law. A department spokeswoman said that, in most cases, offenders were not aware they were breaking the rules.

She added that some drivers fitted approved licence plates to pass vehicle inspection tests and then replaced the legal plates with non-standard ones.

The spokeswoman said some plates had letters or images that made them illegible or difficult to read.

She added: “These licence plates are a matter of concern for the TCD as they present a safety hazard and are ultimately not in compliance with the law.”

The spokeswoman said that all licence plates must have standard-sized black letters on a white reflective background.

Exceptions include loan vehicles, which have a yellow background, and rental minicars, which have red markings on a white background.

All letters or figures on plates should be the same size. She added: “Letters and figures should be seven-sixteenths of an inch broad and the total width of the space taken by any letter or figure, at least one and seven-sixteenth inches.

“The space between any two letters or any two figures shall be three-eighths of an inch, and the space between figures shall be one and five-eighths inches.

“There shall be a margin, between the nearest part of any letter or figure and the top, bottom or sides of the plate, of at least half an inch.”

“No other letters, figures or designs are allowed to be placed near, over or on any letters or figures on the licence plate.”

The only other exception to the rule is personalised plates issued by TCD.

• For more information, contact TCD at 292-1271