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The players involved were condemned as "naive" and "stupid" by former England coach Clive Woodward.

The RFU, pulling the plug on what should have been the curtain-raiser to England's revamped autumn programme, said an investigation had revealed a second incident in which COVID-19 rules were flouted in addition to the 22 October (AEDT) case announced previously.

Former England captain Chris Robshaw was among those in a group of around 12 who broke the rules by leaving the Barbarians hotel on Thursday (AEDT) to have dinner.

That left the invitational side trying to fill gaps in their squad ahead of Monday's (AEDT) match at Twickenham, designed to act as a warm-up for England's delayed Six Nations international away to Italy in Rome next week.

But the RFU said the discovery of a second incident in which the regulations were flouted meant it was left with no option but to call off the match.

"As part of its ongoing investigation into a breach of the COVID code of conduct that took place on 21 October [22 October AEDT], the RFU has discovered there was an earlier undisclosed breach that took place on 20 October [21 October AEDT] when a number of Barbarians players left the hotel bubble without permission," a statement from the governing body read.

It said the potential risk of transmission of the virus meant it had no alternative but to cancel the game.

England coach Eddie Jones had been due to name his side on Saturday (AEDT) but must now travel to Italy without a warm-up match with his men, whereas the Azzurri are in Six Nations action against Ireland this weekend.

As well as the embarrassment at having to call off a game, the abandonment of the fixture won't help the RFU in its quest to get a UK government bailout to assist with the cash crisis caused by the pandemic.

The governing body is also set to lose television money given the match was meant to have been broadcast on Sky Sports.

RFU chief executive Bill Sweeney expressed his frustration at having to call off a match which, although meant to be played behind closed doors, would have been televised.

"We are incredibly disappointed to be calling a halt to this fixture – we know how much fans were looking forward to seeing the teams play," he said.

Harlequins veteran Robshaw apologised on Twitter for his role in the cancellation.

The 34-year-old flanker, for whom the match would have marked a farewell to English rugby before he moves to the United States to play for San Diego Legion, accepted his actions had been "irresponsible".

Former England coach Clive Woodward was left to "shake my head in disbelief" at the "stupidity" of the players. 

The 2003 Rugby World Cup-winning boss said: "These are professional players and they know what's at stake. It's live on TV, it's a game that everyone was looking forward to.

"I can't believe they've been so naive and stupid to think they can get away with it ... It's called a bubble for that reason. 

"Some of the players went out, some of them didn't. Some players listened, some haven't, which makes it even worse in many respects."