"We are aware that some Target gift cards were not fully activated and apologize for the inconvenience," Target spokeswoman Molly Snyder said in an e-mail.

The third-largest U.S. retailer promised to honour the gift cards and said fewer than 0.1 percent of the cards sold during the busy season were affected.

Shoppers can bring the cards to the guest service desk at their local Target stores or call 1-800-544-2943 for assistance, Snyder added.

The news came less than two weeks after the company revealed that hackers had stolen data from up to 40 million credit and debit cards of shoppers who visited its stores during the first three weeks of the holiday season. Target's consumer perception scores dropped to their lowest level since 2007 after the breach, a survey showed.

(Reporting By Dhanya Skariachan; Editing by Cynthia Osterman)

By Dhanya Skariachan