President Trump's chief of staff John Kelly's personal cellphone may have been breached for months, according to a report published Thursday by Politico.

Citing three White House officials, Politico said tech staff believed the phone was compromised after examining it for technical problems. Kelly had been complaining that the phone hadn't been working correctly for months, according to the report.

The chief of staff is no longer in possession of the phone, Politico said. An official said Kelly didn't use the personal phone often since assuming his position in the White House, though Politico said hackers may have been able to access information during Kelly's time as secretary of Homeland Security. The phone may have been breached as far back as December.

It's not clear what data might have been accessed on the phone.