Annie Joseph, secretary general of the News Broadcasters Association (NBA), wrote to the ministry earlier this month, soon after TAM and its joint owners, Nielsen and Kantar, were sued in a New York court by NDTV, which has alleged “wilful negligence and manipulation” of TAM’s viewership data.

NBA – whose president, K V L Narayan Rao, is executive vice chairman of NDTV – has asked the ministry to order an independent audit by a third-party agency to evaluate TAM’s systems, and to direct TAM to stop reporting data while the audit is active.

Ministry sources had previously said it was preparing its own investigation into the claims made by NDTV, while TAM recently met with advertising industry representatives to outline a six-step plan designed to address concerns over its ratings data.

NDTV filed its lawsuit in the New York State Supreme Court in late July. Neither TAM nor Nielsen have yet to publicly comment on the lawsuit, however this week WPP – parent company of Kantar – warned NDTV it was considering a defamation action.

WPP dismissed the claims as meritless and referred to the lawsuit as “hypothetical”, saying neither it nor any of its operating companies had yet been served with court papers.

In response NDTV said “service was indeed made on 10 August” and pointed to the New York State Supreme Court’s website, where a number of affidavits have been filed to say that companies affiliated with both WPP and Nielsen have been served.

“We assume WPP has made a silly error,” NDTV said.

Update @ 3.30pm – A WPP spokesman has responded to NDTV’s affidavits with the following statement:

“We are aware that the New York lawyers acting for NDTV have filed affidavits of service with the New York court claiming to have served the proceedings on various WPP companies. Despite this, valid service has not taken place and we will be drawing the court’s attention to these inadequate and misleading statements in our motion to dismiss the claims in their entirety. There has been a faulty, and clumsy, attempt to serve on one company, but nothing on the others at all.”