Supermarket giant Coles has been fined $7500 after some of its private label loaves of bread sold in three Brisbane shops were found to be underweight.

Regional manager Tammy Banks pleaded guilty on behalf of the company to three shortfall offences in which bread was found to weigh less than the advertised amount on the packet.

The Brisbane Magistrates Court on Friday heard the incidents at New Farm, Redbank and Mt Gravatt over an 18-month period happened because of mechanical failures in the bread-making process.

Most of the loaves were only about five per cent lighter than they should have been, with the greatest discrepancy peaking at 19.8 per cent.

Coles’ lawyer Jamie McPherson said no financial advantage was gained from the incidents and the supermarket had not intended to deceive its customers.

The court heard Coles co-operated with investigators and put in place mechanisms to avoid the shortfalls from happening again.