The two have, according to a report in The Observer newspaper, filed claims under the Public Interest Disclosures Act. The legislation, which is commonly referred to as the "whistleblowers' charter", could lead to the two winning millions in compensation.
It was revealed earlier this year that the two were to sue the marketing services firm for £5m in damages, claiming breach of contract and unfair dismissal, following their sacking in January.
The two, who have been placed on gardening leave for six months, are also claiming loss of income and various options, including shares, which they argue is a result of their dismissal.
Investors and analysts are still waiting for the full story behind the dismissal of the two senior executives to emerge. So far, no reason has been given as to why Miles and Morrison were sacked and the two have been injuncted to prevent further details about their exit emerging.
The two have hired City law firm Campbell Hooper to fight their case, but so far have refused to publicly comment on their case.
The case has put more pressure on Cordiant, already dogged by debt worries and a flagging share price, which is currently languishing at 83.5p.
Last week, merger speculation returned to Cordiant following the announcement of the merger between Publicis Groupe and B|Com3.
Cordiant owns 25% of the Zenith Optimedia Group, which is majority owned by the French advertising group.
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