Saracens winger Chris Ashton maintains that he did not intentionally make contact with the eye area of Ulster's Luke Marshall after failing to overturn a 10-week ban that ruled him out of the Six Nations.
Ashton was found guilty of the offence committed during last month's European Champions Cup clash between the sides, but lodged an appeal against the ruling stating that the punishment was disproportionate.
However, a three-man Appeal Committee met in London and informed Ashton that the ban will not be lifted or reduced, thus ending his hopes of resurrecting his England career under new head coach Eddie Jones at the Six Nations.
Ashton has 39 England caps, but was regularly overlooked by former coach Stuart Lancaster and his last international appearance came against New Zealand in June 2014.
The 28-year-old noted his regret at missing out for his country, but vowed to work hard during his ban, which lasts until March 28.
"I'm incredibly disappointed with the decision, but I now plan to look ahead to the rest of the season and work as hard as I can during my ban," Ashton told Saracens' official website.
"I'd like to thank Saracens and my legal team for all their hard work and support throughout this. I vehemently maintain that I have never made an attempt to intentionally make contact with the eye area of any other player.
"To miss out on the chance to represent my country and Saracens during this period is extremely disappointing, but the judgement stands and it is one that I will respect and accept."
Saracens director of rugby Mark McCall added: "The club has been fully supportive of Chris throughout this process and wanted to ensure that everything possible was done to support his case.
"Saracens and Chris are obviously disappointed by the ramifications of the news, but we now have to accept this decision. We are thankful to the Appeal Committee for considering Chris's case and for the opportunity to put his case forward.
"Chris now plans to work hard during this enforced time away from playing to ensure that after his suspension he can perform well for Saracens, and help the club to a successful season."