About two-thirds of Americans who work at small businesses will see health-insurance premiums increase under Obamacare, according to a new federal report.

The higher premiums will affect about 11 million Americans, according to the report from the Centers for Medicare and Medicaid Services. The report also estimated an additional 6 million individuals will see reductions in their premiums.

The report was released Friday, but came to light late Monday as some lawmakers have seized on the report's release to voice their skepticism about Obamacare.

House Speaker John Boehner, late Monday, released the following statement in response to the report. "For all the promises of lower costs for small businesses, the administration now admits that far more of these workers will pay higher than lower premiums under the law," he said.

"The bad news keeps mounting and our nation's best job creators are paying the price," said House Small Business Committee Chairman Sam Graves (R-Mo.) in a statement. "Earlier this month, the nonpartisan Congressional Budget Office provided economic data that echoed what many small businesses have been telling us – that the health law is killing jobs and harming the economy," Graves said.

The report can be found here.

(Read more: Why there are fewer new US businesses and jobs)