Media organisations have joined forces at a corruption inquiry to fight a suppression order over a controversial chain of emails involving a "very well known person" and a Liberal identity.

The emails, headed "Re Carbon Tax", were suppressed at the Independent Commission Against Corruption on Thursday after questions were raised about whether publishing the documents would breach parliamentary privilege.

Megan Latham presides over ICAC. Credit:Nick Moir

Robert Newlinds, SC, the barrister for NSW Liberal Senator and former party president Arthur Sinodinos, wrote to the ICAC to alert the commission to the potential breach.

"The letter we wrote simply said that we were somewhat perturbed that there may be a breach by counsel assisting [Geoffrey Watson, SC] and the commission of the federal Parliamentary Privileges Act," Mr Newlinds told the hearing on Thursday afternoon.