RTE has apologised to viewers after an "enormous and embarrassing" technical glitch had Russian ambassador Maxim Peshkov repeating the same phrase incessantly during last night's Prime Time.
During a sound loop the ambassador was heard repeating the phrase "Irish Ukrainians, not Russians" over and over again.
But the pictures kept moving in the normal way, leading to massive confusion for viewers.
RTE was bombarded with calls, and Prime Time presenter David McCullagh jokingly tweeted: "It was all right leaving here."
RTE managing director of news and current affairs Kevin Bakhurst took a more serious tone and issued an apology to viewers.
He tweeted: "Many apologies to those watching RTE One and #rtept – the engineers were aware and trying to sort. Not acceptable fault. Infuriating."
He later tweeted that Prime Time would cover the Ukrainian situation again.
"We don't know why it was happening," said an RTE staffer last night. "We don't know what the issue is, but everyone is taking calls on it."
Twitter lit up as the audio loop continued and #irishukrainiansnotrussians began trending along with #rtept.
Even when RTE broke for adverts, the phrase "Irish Ukranians, not Russians" continued to be heard until finally the audio feed was restored during a shampoo commercial.
An apology was later read out by the continuity announcer and a Prime Time statement said: "Many apologies for the enormous and embarrassing technical problem on PT tonight. Engineers were on to it straight away, but difficult to stop."
It is the latest technical glitch to hit a high-profile RTE programme after its Eurosong scoreboard caused confusion on last Friday's Late Late Show.