There's been a major security breach at a consumer credit rating agency that collects personal information on millions of Canadians.

Equifax confirmed Monday that someone has hacked into its database and stole hundreds of credit reports.

Equifax is one of the biggest credit rating agencies in the country and has all kinds of information on Canadians. The company collects detailed personal information about consumers: home addresses, social insurance numbers, bank account balances, credit card and payment histories.

The information is accessed by banks, retailers and insurers to determine whether applicants should be granted credit cards, car leases, loans, and insurance.

Now it appears someone else has been tapping into Equifax's database. A statement from Equifax's Ontario head office says "Credit reports of 1,400 consumers, primarily in B.C. and Alberta, were accessed by criminals."

The criminals were "posing as legitimate credit grantors."

Though the company only announced the security breach on Monday, the RCMP has been investigating for the past month.

"The RCMP is in fact looking into this matter," confirms RCMP Sgt. John Ward, but would say no more.

It's not the first trouble for Equifax. The company was targeted by criminals two years ago, stealing 2,500 credit reports from mailboxes. Using the information, the thieves applied for new credit cards.

Equifax responded to the breach by replacing digits in its printed statements with X's.

In this latest case, it's not clear how Equifax discovered the security breach or how the criminals were using the personal information. But Equifax has begun sending letters to hundreds of people who likely have no idea someone has their personal information.

The company says for the next year, it will monitor each file that was breached, and alert other credit agencies to what has happened.

If you have any concerns about your credit file you can call Equifax. The toll-free hotline is 877-249-2705.