Multiple sources close to the companies confirmed this weekend that a consortium of the newer channels will announce the move this month. It is believed that the existing system has served up "anomalies" that force the channels to question its validity.

"If the numbers are to be believed, " said an executive at one of the stations involved, "Ireland is the only country in the developed world where the audience for terrestrial channels has gone up, and the audience for satellite and digital channels is going down, at exactly the moment when we've become the second-highest percentage of digital homes in Europe."

They cite as one example an audience measurement that more housewives and children than adult men watched Setanta Sports in May, which is highly unlikely.

Sky One viewing figures were reported by the system to have dropped up to 50% recently, which was found to be due at least in part to a technical fault.

The move would divide the advertising community, which relies on the Nielsen ratings to gauge the relative value of airtime for advertising.

"We don't want two currencies, " said the MD of one media buying firm. "But a lot will depend on the credibility of who they get as a partner."

It is understood the companies have been in discussions with research firm TNS/MRBI to run the service, which would have a start-up cost of around 4m and take 12 months to be up and running.

The companies involved have long been dissatisfied with the "granularity" of audience measurement provided by the Nielsen ratings, which rely on a panel of 600 viewers whose TV sets are meant to report automatically their viewing habits. The newer channels argue this panel is too small to accurately measure smaller subsets of audience in a multi-channel environment and have argued for a panel of at least 1,000 viewers.

Nielsen and RTE have argued that the figure of 600 is statistically valid for a market of Ireland's size.

Executives at the companies involved said they did not believe their audience shares would rise instantly under a new system, but they argued that the current system denies them specific enough information to compete. And RTE effectively controls how the research is conducted, they said.

"We don't have enough confidence in the data to make programming decisions. Yet, in 2007, we will be expected to pay more than RTE, " said Pat Donnelly, executive chairman of Channel 6. "RTE has 200m in ad revenue. When we've our plus-one channel and music channel up and running, we'll have maybe 5m in ad revenue. Does that seem fair?"

While Donnelly would not confirm the move, he added:

"We're not happy with the research, we're not happy with the sample size, we're not happy with how we're being treated. And we won't sit there and take that shite."

RTE was unable to comment by deadline for this story. Messages left at AGB Nielsen were not returned by press time.