Moscow:
The twin blasts that killed three people and injured scores at the Boston marathon are a warning for Russia as it prepares to host the 2014 Winter Olympic Games, the sports minister said on Tuesday.
"For Russia, which will have to soon stage a number of major sporting events, this is a serious warning bell," RIA Novosti quoted Vitaly Mutko as saying.
Besides the 2014 event in the Black Sea resort of Sochi, Russia will also host the University Games in Kazan later this year, as well as the 2018 Football World Cup.
The Sochi Games will be staged on the edge of the restless North Caucasus, where Russia waged two post-Soviet wars in Chechnya, and where violence is prevalent in nearby Dagestan.
Mutko said Russia was "very worried" about security at all the sporting events.
"We will be devoting special attention to it," he said.
Separately, the Kremlin said that Russian leader Vladimir Putin sent US President Barack Obama a message of condolences in which he condemned "this barbaric crime."