The personal cellphone of White House Chief of Staff John Kelly was compromised, U.S. officials believe.

Politico, citing three unnamed government sources, reported Thursday that the issue may potentially date to December, when Kelly was still head of the Department of Homeland Security.

A White House official told Politico that Kelly uses his government-issued phone for any official communication and has not used his personal phone since joining the Trump administration.

The official reportedly did not dispute the Politico report. FoxNews.com could not immediately confirm the story.