NEW YORK — Neiman Marcus says customers’ Social Security numbers and birthdates to its knowledge were not stolen in a security breach that happened over the holiday season.

The update, posted on its website Thursday, comes nearly a week after the Dallas-based luxury retailer said that thieves stole some of its customers’ payment information and made unauthorized charges. That follows Target’s announcement of a massive security breach that could be the largest on record for a retailer when a final tally is known.

Neiman Marcus had said it was notified in mid-December by its credit card processor about potentially unauthorized payment activity and on Jan. 1, a forensics firm confirmed that it was a victim of a cybersecurity intrusion. Neiman Marcus has not said how many customers have been affected.

First Published January 16, 2014, 8:55 p.m.