The House oversight committee is ramping up pressure on anyone who had access‎ to Hillary Clinton's personal server and classified files -- including her lawyers and aides who may not have had sufficient clearance.

‎Committee Chairman Jason Chaffetz, R-Utah, requested new details on who had access in a letter sent Monday to FBI Director James Comey and reviewed by Fox News.

In his letter, Chaffetz asks Comey if the FBI ever investigated the possibility that Clinton's classified emails were improperly stored or accessed by her personal representatives or by anyone at the law firm Williams & Connolly LLP, including on "any unauthorized electronic devices or media, such as desktops or servers."

He also asks for the FBI's conclusion if it did investigate that. 

Additionally, Chaffetz asks for "the manner in which Clinton's personal representatives and individuals at Williams & Connolly stored any electronic devices and media and physical documents" containing any classified emails, in addition to the FBI's "assessment of whether that met applicable security requirements."

During his testimony on July 7, Comey was asked if Clinton gave people without a security clearance access to classified information, to which he replied, "Yes, yes."

He also said that Clinton's attorneys did not have necessary security clearances, and when asked further if it concerned him, Comey replied, "Oh yeah, sure."

Comey said that between 2 and 10 people had access to the servers without appropriate clearance. Clinton used non-government IT management companies such as Colorado-based Platte River Networks.

When asked during his testimony if there was any consequence to an attorney looking through emails without a proper security clearance, Comey said while there were "not necessarily criminal consequences, but there's a great deal of concern about an uncleared person, not subject to the requirements we talked about in the read-in documents, potentially having access."

"That's why it's very, very important for us to recover everything we can back from attorneys," Comey told the committee.

Fox News' Catherine Herridge contributed to this report.