Sam Jones was one of the surprise inclusions in England’s squad for the autumn internationals but the Wasps flanker will not be making his Test debut this year after breaking his right leg in a judo session at a national training camp in Brighton.

The 24-year-old Jones was being considered as a replacement for his injured club-mate James Haskell at openside flanker but his unavailability means Eddie Jones is likely to pick Chris Robshaw and Maro Itoje as the flankers against South Africa next month and operate them on a left and right basis rather than open and blind.

It is understood Jones and Maro Itoje were putting into practice what they had been taught by British Judo coaches JP Bell and Kate Howey when injury struck on Tuesday morning.

The players had been practising skills that England believe might prove useful at the breakdown and in the tackle.

Jones had an x-ray on his injured leg which revealed a fracture and he will have a scan on Friday to find out the extent of the damage and when he can expect to be back in action. “I feel for Sam,” said Dai Young, the Wasps director of rugby. “He has worked his socks off for us and was deservedly called up by England.

“He has been one of the first names on my team-sheet this season and my biggest disappointment for him is that he has been playing so well. I am sure he would have made a good impression on the England camp and you cannot help but feel sorry for him. It’s too soon to know how long he will be out but our medics and physios will look after him and we look forward to having him back when he is ready.”

Jones is the third England back-row to be ruled out of the autumn campaign, after Haskell and Jack Clifford, and Eddie Jones also has concerns over the fitness of his captain, Dylan Hartley, and Owen Farrell, who has featured mainly in the centre for his country this year. Hartley has not played since coming off at half-time with a back problem during Northampton’s second match of the season at Bristol more than three weeks ago while Farrell has not featured since the summer tour to Australia because of back and hip problems that have left him unable to kick without pain.

England play South Africa on 12 November but Northampton do not know when Hartley will return to action. “He is improving,” said the club’s attack coach, Alex King. “He went to Brighton with the England squad and returned to us on Wednesday. He is responding well and I do not think he will be too far away. We have not set a date on when he will be back.”

King said that Luther Burrell, who was taken to hospital after suffering concussion during the Premiership defeat by Saracens last month, is close to being available for selection again. The midfielder was knocked out after mistiming a tackle on Brad Barritt.

A series of concussions has ended the career of the South Africa and Saracens second-row Alistair Hargreaves, who has retired at the age of 30 after taking medical advice. “It was a very tough decision to take but after a number of concussions in the last two seasons I have come to the conclusion that the risk is outweighing the reward,” said the champions’ former captain.

“I have a young family and have to take decisions that are right by them. I feel this is the right one. Saracens have been amazing to me ever since I walked through the doors, but especially over the last 12 months when I have been suffering from injuries and concussion. They have been a constant source of support in a really emotional and difficult time.

“The first person I spoke to about this was Mark McCall [the director of rugby] and he was completely supportive. This club puts people first and their interests throughout have been ‘what’s best for me and my family’ and I’m extremely grateful for the way they have handled the matter.”