It follows yesterday’s reports that ex-chief reporter Neville Thurlbeck is taking the company to an employment tribunal over the same claims.
Edmondson, 42, and Thurlbeck, 50, were both arrested in April on suspicion of conspiring to intercept voicemail messages while working at the News of the World.
Edmondson was sacked from the Sunday tabloid in January after evidence allegedly emerged linking him to phone-hacking.
It came days after former NoW editor Andy Coulson resigned as Prime Minister David Cameron’s director of communications after admitting claims about illegal eavesdropping under his command were making his job impossible.
According to reports, Edmondson – unlike Thurlbeck – is not claiming he was a whistleblower.
A preliminary hearing into Thurlbeck’s case will take place at the East London Tribunal Service centre on Friday
News International has promised to “vigorously contest” both cases.
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