Hillary Clinton
Hillary ClintonReuters

The company that managed Hillary Clinton's private email server said it has "no knowledge of the server being wiped," indicating that tens of thousands of emails Clinton said were deleted could be recovered, Reuters reported Saturday.

Clinton, the front-runner for the Democratic presidential nomination, and her aides have said she deleted her personal emails from her time as secretary of state, but unless the server has been "wiped" experts say those 31,000 emails could be recovered, according to the news agency, which cited a report in The Washington Post.

A representative of the Clinton campaign could not immediately be reached for comment on the report.

Clinton is facing criticism for having used a personal email address during her entire four years as secretary of state, despite the fact that under specific guidelines signed into law by President Barack Obama, government email accounts are supposed to be used in any situation involving official business.

Clinton has said she used private emails out of "convenience", though she has also admitted it "would have been better" to have two accounts to separate work and personal emails.

An internal government review has found that she sent at least four emails from her personal account containing classified information during her time heading the State Department.

Last week, Clinton apologized for the use of a private email server, even though she had insisted she didn’t need to apologize because "what I did was allowed."

Denver-based company Platte River managed the server.

"Platte River has no knowledge of the server being wiped," company spokesman Andy Boian was quoted as saying by The Washington Post. "All the information we have is that the server wasn't wiped."

Republican Senators Charles Grassley and Ron Johnson, chairmen of the Judiciary and Homeland Security committees, respectively, said they would push for the deleted emails to be reviewed if they can be recovered, The Post said.