A recent letter from the U.S. Senate​ revealed that Wells Fargo's scandal over fraudulent account activity had extended to small business owners, raising more questions about the bank's level of damage.

On Wednesday, Steve Chabot, the chairman of the U.S. House of Representatives Small Business Committee, demanded further information in letters addressed to Small Business Administration (SBA) head Maria Contreras-Sweet, and Wells Fargo CEO John Stumpf. The letters questioned whether or not Wells Fargo's SBA-backed loans were among those affected.

"As a partner with SBA in these programs, Wells Fargo has the ability to help small business owners access needed capital to start and grow their businesses," Chabot said in his letter to Stumpf. "This cannot happen, however, if customers are not able to trust their bank to properly manage their accounts."

Senator David Vitter's own Sept. 20 letter to the Small Business Administration revealed that Wells Fargo is the SBA's largest lender with $7.14 billion in active loans, guaranteed by taxpayers.

As many as 10,000 businesses have reportedly been affected by the bank's fraudulent activities, and charged extra fees from the unauthorized accounts, according to sources cited by Reuters.

Business owners are encouraged to take steps to see if there are any unauthorized accounts under their names. This might be challenging to do online, since the CFPB revealed earlier this month that fake emails and PIN numbers were used, but calling the bank to verify all accounts attached to your name would be a good first step. Additionally, credit scores may be affected by unauthorized credit cards, so it's important for account holders to diligently check credit reports for any unfamiliar items and extra fees.