At least five European countries' Olympic committees received letters in Russian on Wednesday making a "terrorist threat" before the Sochi Games, but Olympic chiefs said they posed no danger.
Despite the assurances, the letters to committees in Italy, Hungary, Germany, Slovenia and Slovakia briefly caused alarm and underlined nervousness over security at the $50-billion event on which President Vladimir Putin's legacy may depend.
Suicide bombers killed at least 34 people in a southern city last month, Islamist militants have threatened to attack the Winter Games and security forces are hunting a woman suspected of planning a suicide bombing and of being in Sochi already.
"I am very pleased to inform everyone that both the International Olympic Committee and the Sochi organizing committee … declared after an analysis of the letter that this threat is not real," Zsigmond Nagy, director of international relations at the Hungarian Olympic Committee, told Reuters.
He said "this person has been sending all kinds of messages to many members of the Olympic family."
The letter, he said, threatened Hungarian nationals, competitors and officials, saying that "persons attending the Olympic Games might be blown up."
Nagy also quoted IOC officials, saying the letters had been sent by someone living outside Russia who had carried out such hoaxes before, but did not identify the person.
"This threat is not a real one and there is nothing to worry about," he said.
Officials in Italy, Germany, Slovakia and Slovenia said their national committees had also received threats and all had passed them to police.
The IOC, which is based in Switzerland, moved quickly to ease concern after the first of the letters was received in Budapest. It said it took security very seriously and passed on any credible information to the relevant security services.
"However, in this case it seems like the e-mail sent to the Hungarian Olympic Committee contains no threat and appears to be a random message from a member of the public," it said.