U.S. bank Wells Fargo has fired more than 5,000 of its employees and been fined a total of $185 million US for making up millions of unauthorized bank accounts on their customers' behalf — often without the customers' knowledge.

The California-based bank will pay $100 million US to the Consumer Financial Protection Bureau (CFPB), $35 million US to the Office of the Comptroller of the Currency and $50 million US to the City and County of Los Angeles along with restitution to customers for a scam dating back to 2011 that allowed the bank to rack up millions in bank fees and meet aggressive growth targets.

According to its most recent regulatory filings, Wells Fargo has 70 million customers worldwide.

According to a lawsuit filed in California's superior court, the bank aggressively pushes its employees to sign up customers for more accounts and products, and rewards them for doing so. Four times a day, the lawsuit alleges, managers review how many new accounts have been opened and reprimands employees who have not met their quota.

"Wells Fargo thus puts its employees between a rock and a hard place," the statement of claim reads, "forcing them to choose between keeping their jobs, and opening ... accounts." 

Many apparently chose the latter, as according to the CFPB, Wells Fargo employees opened 1.5 million bank accounts and more than 500,000 credit cards without the expressed permission of their existing customers. Money in customers' accounts was transferred to these new accounts without authorization. Debit cards were issued and activated, as well as PINs created, all without telling customers what they were doing.

In some cases, Wells Fargo employees even created bogus email addresses and other contact information to sign up customers for online banking services and earn an employee bonus as a result.

"Wells Fargo employees secretly opened unauthorized accounts to hit sales targets and receive bonuses," CFPB director Richard Cordray said.

Some 5,300 employees have been fired as a result of their role in the scheme. Wells Fargo says it has already refunded $2.6 million to its customers, an amount that will likely rise because the bank has only examined about one per cent of its total customer base so far. The average rebate has been about $25 US.

In a statement, the bank said it is "committed to putting our customers' interests first 100 per cent of the time, and we regret and take responsibility for any instances where customers may have received a product that they did not request."

Wells Fargo is still known for having aggressive sales goals for its employees. Wells Fargo's executives highlight every quarter the bank's so-called "cross sale ratio," which is the number of products the bank sells to each of their individual customers. The ratio hovers around six, which means every customer of Wells Fargo has on average six different types of products with the bank.

According to the lawsuit, employees have been known to sign up friends and family members for accounts in order to meet their quotas. 

With files from The Associated Press