The chairman of the congressional committee probing the Benghazi terror attacks has formally asked that Hillary Clinton turn over her personal server -- warning that the House could take steps to pressure her if she refuses. 

Rep. Trey Gowdy, R-S.C., sent a letter, released Friday, to Clinton's attorney requesting that the former secretary of state "relinquish" the server to a "neutral, detached and independent third-party" for review. 

The server has become a point of controversy after she admitted to exclusively using a private email account and a personal server while secretary -- yet insisted her server would remain private, though some lawmakers want access to it to ensure she's turned over all official emails during her tenure. 

Gowdy's letter suggested that Clinton could turn the server over to the State Department inspector general for review. He said it's important for a third party to look over the contents to ensure any public documents are released. 

"Her arrangement places her as the sole arbiter of what she considers private and what is beyond the view of the public," Gowdy said in the letter addressed to her Washington attorney Friday. 

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One source told Fox News that Gowdy's committee does not have the statutory authority to subpoena the server itself -- only witnesses and documents. However, the full House does, should it escalate to that point. 

At the end of his letter, Gowdy asked for a response by April 3. He pointedly warned that if Clinton won't comply, he will tell House Speaker John Boehner so he can use the "full powers" of the House to take the "necessary steps." 

Gowdy has expressed concern that because Clinton was using a personal email to conduct business as America's top diplomat from 2009 to 2013, lawmakers cannot be confident that the official Benghazi investigation has received all pertinent communications involving Clinton and other government officials at the time. 

Her office has turned over more than 30,000 "work-related" emails and, responding to the media uproar caused by the revelations this month, asked the State Department to make them public. Her office acknowledged that she established a private server, and that she deleted what she described as personal emails from the account. 

She said that in hindsight, it would have been better to use the government account. But she assured that all the official emails were saved and turned over to the State Department for their official archives. 

Gowdy voiced doubts in a written statement Friday, separate from the letter. 

"An independent analysis of the private server Secretary Clinton used for the official conduct of U.S. government business is the best way to remove politics and personal consideration from the equation," he said in the statement. 

"Having a neutral, third-party arbiter such as the State Department IG do a forensic analysis and document review is an eminently fair and reasonable means to determine what should be made public. " 

Fox News' James Rosen contributed to this report.