A group of 14 U.S. speedskaters that includes five Olympic bronze medalists has boycotted the team, accusing the head coach and his two assistants of vast, unchecked abuse, according to newspaper reports.

In a Tuesday letter to U.S. Olympic Committee chief executive Scott Blackmun, the group's attorney demands an investigation so the speedskaters "are not denied their opportunity to participate in the upcoming World Cup international short-track competitions, free of abuse, both physical and mental, that they have suffered in the hands (literally) of Jae Su Chun and his two assistant coaches."

Allison Baver is among a group of 14 U.S. speedskaters that has boycotted the team as long as Jae Su Chun is coach. They are accusing him of vast abuse. Jamie Squire/Getty Images

The letter follows a wider grievance against U.S. Speedskating filed two weeks ago that includes five more speedskaters and a code-of-conduct complaint against Chun with U.S. Speedskating.

"U.S. Speedskating takes this grievance very seriously and we intend to investigate each and every allegation," said Tamara Castellano, the federation's communications and marketing director, in a statement, according to the Chicago Tribune and The Salt Lake Tribune reports.

The speedskaters, among them 2010 Vancouver bronze medalists Allison Baver, J.R. Celski, Alyson Dudek, Travis Jayner and Jordan Malone, say Chun and assistants Jun Hyung Yeo and Jimmy Jang have engaged in discrimination against women, inappropriate sexual conduct and have provided alcohol to minors.

Apolo Anton Ohno and top U.S. women speedskaters Katherine Reutter and Lana Gehring were not among the complainants.

Reutter is an athletes' representative on the U.S. Speedskating's board of directors, which meets Saturday.

Chun is alleged to have slammed a skater against a wall before hitting him repeatedly for "disrespecting" the coach. The alleged abuse also included screamed insults in front of staff members and fellow athletes, tantrums in which chairs and sports equipment were thrown, athletes forced to train despite injury and humiliating treatment that included women being called "fat" and "disgusting" and told to "stop eating," according to the Salt Lake Tribune report.

"You are worthless," Chun allegedly said to one speedskater, according to the Salt Lake City newspaper.

Chun declined comment through a spokeswoman, the report said.

"These are obviously serious allegations, and we are working closely with speedskating to look into this and fully understand the issues in this case," USOC spokesman Patrick Sandusky said.

The scandal erupts in Chun's fifth year as U.S. coach and reaches the top of the U.S. Speedskating hierarchy, with CEO Mark Greenwald the subject of another code-of-conduct complaint leveled by skater Levi Kirpatrick in which Greenwald is accused of neglect of duty and intimidation.

Lured from the South Korean national team, Chun helped shape a 2010 Vancouver short-track team that won six medals.

Jang is a former U.S. Speedskating developmental coach of the year who Russia dismissed last year as its coach because of "cruel training methods," the Salt Lake Tribune report said, citing media reports.

The speedskaters' attorney, Edward Williams, asks in the letter for "prompt action" by the USOC with the U.S. team beginning qualifying sessions at the end of this month for the World Cup season.

"My clients are being faced with the choice of again skating under and for a known abusive coach or ending their racing career," Williams wrote.