The unidentified hackers say they carried out the attack to raise awareness of a security loophole in the database of the social media application.
In a statement emailed to website TechCrunch, the hackers said: "Our motivation behind the release was to raise the public awareness around the issue.
"It is understandable that tech start-ups have limited resources but security and privacy should not be a secondary goal.
"Security matters as much as user experience does.
"You wouldn't want to eat at a restaurant that spends millions on decoration, but barely anything on cleanliness."
The alleged database was originally published online with two digits of the phone numbers redacted.
The link was down when
The attack comes a week after internet security firm Gibson Security warned the site could be vulnerable to attack.
Snapchat responded by publicly labelling the weakness "theoretical".
Gibson Security has set up a database search facility where concerned account holders can enter their username to see if their account has been compromised.
According to the company, only the account details for users in some areas of the US were hacked.
A message on its website said: "Are you part of the recent 4.6 million Snapchat user leak? Let's hope not. Enter your username below to find out.
"NB Only specific areas of America were included – if you're outside of America or not in an area code detailed here you're probably fine."
An employee of Gibson Security explained to
"Snapchat has a feature which uploads your address book to their server as well as your phone number, and compares the phone numbers in your address book to the phone numbers of Snapchat users.
"This feature exists in other applications and is fundamentally broken; one could iterate through ranges of mobile phone numbers and match usernames to phone numbers."
Snapchat claims on its website to take the privacy of its users seriously: "We take reasonable measures to help protect information about you from loss, theft, misuse and unauthorised access, disclosure, alteration and destruction."
Created by students at
Most Popular Stories
- Obama Administration Releases Proposal to Regulate For-Profit Colleges
- Koch Brothers Step up Anti-Obamacare Campaign
- Elizabeth Vargas' Husband Marc Cohn Addresses Rumors
- Keurig Adds Peet's coffee, Alters Starbucks deal
- U.S. to Relinquish Gov't Control Over Internet
- Quiznos Files for Chapter 11
- Vybz Kartel Convicted of Murder
- FDIC Sues Big Banks Over Rate Manipulation
- SoCalGas Reaches Record Spend on Diversity Suppliers
- U.S. Consumer Sentiment Falls in Early March