National Security Agency (NSA) whistleblower Edward Snowden has accused the US of regularly sharing personal information about its citizens of Arab and Palestinian descent with Israel.
In an interview with the New York Times, Snowden said the NSA "routinely passed private, unedited communications to Israel".
Documents leaked by Snowden appear to show that the US gave "unevaluated and unminimised transcripts, gists, facsimiles, telex, voice and Digital Network Intelligence metadata and content", to Unit 8200, a secretive Israeli intelligence department.
Snowden feared the intercepts included email and telephone communications of Arab and Palestinian-Americans, whose relatives in Israel and the Palestinian territories could become targets based on the information, he said.
The former NSA contractor, who has now been granted asylum in Russia, said this is "one of the biggest abuses we've seen", Times writer James Bamford reported.
Bamford cited a document that shows the close relationship between the NSA and Unit 8200, and that outlines the transfer that have occurred since 2009.
Snowden is wanted by the US on espionage charges after leaking thousands of secret NSA documents to The Guardian in June 2013.
The 31-year-old fugitive has been granted a three-year residency in Russia that allows him to travel abroad.