A 23-year-old rugby player was fined #1000 by a sheriff yesterday for throwing a punch that broke another player's jaw, despite letters in his support from Scotland Grand Slam captain David Sole and Scotland 'A' captain Jeremy Richardson.

Jason Fayers, a newly qualified vet, has already been suspended for four years by the Scottish Rugby Union for the punch that floored Kelso prop forward Craig Halliday in a Kelso v Edinburgh Accies match at Poynder Park last September.

Yesterday, as he emerged from Jedburgh Sheriff Court, Fayers declined to comment. His lawyer George More said: ''In view of the fact that he has an appeal pending with the SRU he does not want to say anything.''

The court heard claims that Fayers, who admitted a charge of assault to severe injury, had been persistently impeded throughout the first half of the game by his opposite number, Craig Halliday, in what Mr More described as ''the jungle of the lineout''.

He punched Mr Halliday once and that put him in hospital with a double fracture of the jaw which required the insertion of strengthening metal plates.

The referee did not see the incident and Fayers was not penalised on the pitch, but after examining TV footage of the game the procurator-fiscal at Jedburgh, Graham Fraser, decided to bring a criminal case.

What happened on the pitch, however, was part of a recognised unofficial code among players, according to letters read out by George More from Fayers' fellow Accies club members David Sole and Jeremy Richardson.

The letters, claimed Mr Fraser, reflected a ''cynical view'' that this was all part and parcel of the game.

Mr More said there was an unwritten code that if an opponent persistently broke the rules and the referee did not see it or act on it, ''you sort it out yourself''. Jeremy Richardson's letter said: ''If someone insists on infringing I will tell my blocker to sort it out. In a game which is a matter of confrontation this will invariably be by a punch.''

David Sole cited an instance were he received a broken nose but took no action because ''I did not want the game I love to be dragged through the courts and also because at the time I was also infringing. After a punch-up tempers cool and the problem is solved.

Mr More said that Fayers, now working as a #20,000-a-year vet at a Southampton practice, had already been punished by the SRU and could not play anywhere in the world for four years. His rugby career was effectively over and he now had a criminal record for assault.

Sheriff James Paterson ordered Fayers to pay #500 compensation to Mr Halliday.

Last night Edinburgh Accies, for whom Fayers played while studying at the Royal Dick Veterinary College, issued a statement saying: ''It is a matter of deep sadness to the club that events during our match against Kelso have led to Jason being convicted of a serious criminal offence. Jason is a personable and likeable young man.''

Kelso secretary Norman Anderson said:" I wouldn't wish to make any comment on the sentence imposed by the court.''

Legal action is still pending in the case of an Edinburgh Wanderers player who was cited after an alleged incident in a match against Portobello.