On Wednesday, the Boston Athletic Association (B.A.A.) announced its decision to ban athletes residing in Russia and Belarus from participating in the marathon and 5K run, among the best-known in the world, set to take place on April 18.
"A total of 63 athletes will be removed from the Boston Marathon and B.A.A. 5K collectively," the B.A.A. spokesperson said when asked about the total number banned from the two countries.
Citizens of both countries who live abroad will be able to compete without their national flags.
Organizers said they will make "reasonable efforts" to refund the athletes from Russia or Belarus, within the constraints as imposed by federal and international sanctions. However, the spokesperson did not comment on how they are going to return this money.
The Boston marathon is the oldest one in the world. The first race took place in 1897. Over 30,000 athletes expect to run this year.
Three Russian athletes - Olga Markova, Svetlana Zakharova and Lidya Grigoryeva - won the marathon in 1993, 2003 and 2007.