A former British spy who was a source for the FBI in its probe of Donald Trump's presidential campaign had an extended friendship with Ivanka Trump, the president's daughter, a source familiar with the friendship said on Monday.

A friendship between Christopher Steele, a former officer of British foreign intelligence agency MI6, and an unspecified Trump family member was laid out in a report by the U.S. Justice Department's Inspector General published on Monday. The report looked into elements of how the FBI handled its investigation into whether Donald Trump's 2016 presidential campaign had colluded with Russia.

The FBI used Steele's work as part of its investigation.