The ABC’s flagship news program Four Corners is in crisis following explosive claims a reporter used a colleague to play three different sources in two separate documentaries.

It’s alleged the same person played the roles of a drug dealer, a reformed addict and a security operative across the programs.

WATCH THE VIDEO ABOVE: Four Corners in crisis over fake sources scandal

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The reporter, a former bikie, has already been sacked from the broadcaster.

Both programs have been pulled from circulation and multiple internal investigations have been launched into the scandal.

Senior ABC staff are now being questioned as part of the probe, in what’s being described as one of the biggest scandals in the program’s 65-year history.

The reporter allegedly used a colleague for three different sources in two documentaries. Credit: 7NEWS