Disgruntled hackers targeted the Brazilian Olympic Committee's website to complain about the country's poor performance at the Beijing Games.
The hackers replaced regular content with criticisms of Brazilian athletes, the committee said on Tuesday.
"Brazil stinks in these Olympics" was one of the messages posted, according to the Universo On Line news service of the Folha de S. Paulo newspaper.
Brazil was in 39th place with one gold and five bronze medals late Tuesday.
The site was not operating for several hours, including during the Brazil-Argentina semifinal football match which Argentina won 3-0.
"Dear user, our site is temporarily off ... for maintenance reasons," the committee said in a statement on its site. "We will return soon with news of our delegation in Beijing."
By mid-afternoon, the site was back on.
