WASHINGTON (Reuters) - U.S. lawmakers said on Wednesday there was evidence of a "dangerous pattern" of safety lapses at government laboratories dealing with dangerous pathogens such as anthrax and avian flu that required a change in culture at the U.S. Centers for Disease Control and Prevention.

Members of a House Energy and Commerce Committee subcommittee cited new information on breaches previously unreported by CDC, which is under scrutiny for the potential exposure of more than 80 lab workers to live anthrax bacteria in June. No one has fallen sick due to the lapses.

The criticism, equally shared by Democratic and Republican lawmakers, was directed at CDC Director Dr. Thomas Frieden at a hearing. The repeated breaches at the CDC have sparked fresh concerns over the lack of independent oversight of potentially dangerous research nationwide, even as the number of labs doing such work has surged in recent years.

Frieden was pressed for answers on why the national public health institute was not prepared to report or prevent dozens of breaches identified by federal investigators, and whether its staff recognized the huge risk to the public if dangerous microbes were to escape its labs.

"A dangerous, very dangerous pattern is emerging and there are a lot of unknowns out there," Committee Chairman Fred Upton, a Michigan Republican, said at the hearing. "Why do these events keep happening?"

Frieden replied that the agency was instituting sweeping measures to improve internal controls on such research. It has already announced the closure of two labs responsible for the release of pathogens and suspended any sample transfers from all of its high-security labs.

"In hindsight, we realize we missed a crucial pattern: a pattern of incidents that reflect the need to improve the culture of safety at CDC," Frieden said.

In the case of the anthrax incident, Frieden reiterated that workers at a high-security CDC lab believed they had inactivated the bacteria before transferring samples to lower-security labs, where workers use less protective gear.

"Dr. Frieden, this is like saying I didn't know the gun was loaded, but somebody got shot," said Tim Murphy, chair of the Oversight and Investigations subcommittee. "But you should always assume it is. For someone to say, 'Well I didn't think the anthrax was live,' is unacceptable."

Federal investigators found dozens of safety and security problems at CDC labs handling dangerous pathogens in the 18 months prior to the release in June of live anthrax to a lab not equipped to work with it, according to a memo by Democratic committee members released on Wednesday.

The investigators, from the U.S. Department of Agriculture, found equipment failures, an inability to document staff training and missing signatures on required biosafety plans.

Other failures included unauthorized access to labs and improperly documenting entries and exits, posing risks to biosecurity, or the theft of potentially lethal microbes.

The findings stem from six inspections at the CDC's Atlanta campus between January 2013 and March 2014.