Uber acknowledged Friday it was the subject of a federal investigation into a software tool it used in the past aimed at interfering with competing ride-sharing operators.

An Uber spokesman told AFP that "we are cooperating with the investigation" after a Wall Street Journal report on the probe, while noting that the tool is no longer being used by Uber.

The report said the FBI and New York law enforcement officials were investigating use of the "Hell" software program which could track drivers for the rival ride-sharing group Lyft.

The US daily said "Hell" allowed Uber to create fake Lyft accounts and to trick the rival system into believing prospective customers were seeking rides in various locations around a city

It added that it also gleaned data on drivers who worked for both companies, to enable Uber to offer incentives to leave Lyft.

The report is the latest in a series of woes for Uber, which replaced its top executive last month as part of an effort to clean up a workplace culture marked by cut-throat competition, sexism and unfair competition with rivals.

Uber noted that a civil lawsuit filed by a Lyft driver over the "Hell" program had been dismissed by a federal court.