FINA, the international governing body for swimming, has written to the US Masters Swimming to advise them to reject Lance Armstrong's entry to take part in a competition scheduled this weekend.
The disgraced cyclist was planning to use the small low-profile event in Austin, Texas, to make a return to competitive sport.
The competition falls under the jurisdiction of the US Masters Swimming. In a statement, the governing body said:
FINA wrote a letter to the US Masters Swimming (with copy to US Aquatic Sports and USA Swimming) requesting not to accept the entry of Mr. Lance Armstrong in the [...] competition.
Lance Armstrong's return to competitive sport this weekend will be against veteran swimmers, a Texas newspaper reported.
Most competitors in the US Masters Swimming event entered by Armstrong will be older than the 41-year-old cyclist, the Austin American-Statesman said.
Armstrong is banned for life from all competitions that adhere to world anti-doping codes, but is allowed to take part in the low-profile Austin swimming event.
US Masters Swimming executive director Rob Butcher said nobody had raised formal objections to Armstrong competing.
Butcher added: "The purpose of our organisation is to encourage adults to swim."
Lance Armstrong is planning to make a return to competitive sport as a swimmer this weekend.
The disgraced American cyclist is entered for the Masters South Central Zone Swimming Championships, which takes place at the University of Texas.
Armstrong is set to compete in freestyle races over 500 yards, 1,000 yards and 1,650 yards at the event in his home city of Austin.
Armstrong was stripped of his seven Tour de France titles last year for being part of a doping scandal.
Lance Armstrong's lawyer says that the Justice Department has joined a fraud lawsuit against the disgraced cyclist.
The US Anti-Doping Agency has claimed that Lance Armstrong "was worried of potential criminal and civil liability" if he gave evidence to them about doping:
We have provided Mr Armstrong several opportunities to assist in our ongoing efforts to clean up the sport of cycling.
Following his recent television interview, we again invited him to come in and provide honest information, and he was informed in writing by the World Anti-Doping Agency (WADA) that this was the appropriate avenue for him if he wanted to be part of the solution.
Over the last few weeks he has led us to believe that he wanted to come in and assist USADA, but was worried of potential criminal and civil liability if he did so.
Today we learned from the media that Mr Armstrong is choosing not to come in and be truthful and that he will not take the opportunity to work toward righting his wrongs in sport.
Lance Armstrong's lawyer has said the cyclist will not be interviewed under oath by a U.S. Anti-Doping Agency official who wanted him to tell them all he knows about doping:
Lance is willing to cooperate fully and has been very clear: He will be the first man through the door, and once inside will answer every question, at an international tribunal formed to comprehensively address pro cycling, an almost exclusively European sport.
We remain hopeful that an international effort will be mounted, and we will do everything we can to facilitate that result.
In the meantime, for several reasons, Lance will not participate in USADA's efforts to selectively conduct American prosecutions that only demonise selected individuals while failing to address the 95% of the sport over which USADA has no jurisdiction.
Lance Armstrong's lawyer has said the cyclist won't be interviewed under oath by a U.S. Anti-Doping Agency official who wanted him to tell them all he knows about doping, according to the AP news agency.
USADA officials had said the disgraced cyclist must speak with them if he hoped to reduce his lifetime ban from sports. Today was the deadline for him to agree to speak to them.
Tim Herman said the process served "only to demonise selected individuals."
Disgraced cyclist Lance Armstrong is being sued by a company that paid him about $12m (£7.6m) in prize money in connection with three of the seven Tour de France titles that have since been stripped from him over his use of banned drugs.
In a suit filed in Texas state court in Dallas, SCA Promotions Inc, alleges Armstrong and his management company, Tailwind Sports, defrauded SCA into paying him the prize money for his 2002, 2003 and 2004 wins
A Spanish doctor who may hold the secrets to drug cheating in football and tennis, has gone on trial in Madrid.
The public health charges against Eufemiano Fuentes relate only to cyclists he worked with.
But the man leading the worldwide fight against doping told ITV News that the doctor was involved with athletes from a variety of other sports. ITV News Sports Editor Steve Scott reports:
Concerns in the cycling world continue in the wake of Lance Armstrong's doping confessions as the Independent Commission has lost the confidence of the International Cycling Union (UCI) and the World Anti Doping Agency (WADA) and will be scrapped.
The Independent Commission was set up in November 2012 to look at a decision by the US Anti Doping Agency into Lance Armstrong and the United States Postal Service (USPS) team.
UCI President Pat McQuaid said:
“As I said last Friday, we have listened carefully to the views of WADA, USADA and cycling stakeholders and have decided that a truth and reconciliation process is the best way to examine the culture of doping in cycling in the past and to clear the air so that cycling can move forward."
The Independent Commission, was chaired by former Court of Appeal judge Sir Philip Otton, and included the UK House of Lords Peer and Paralympic Champion Baroness Tanni Grey-Thompson and the Australian lawyer Malcolm Holmes QC, but the independence of the board has been called in to question.