• Sports: Attack raises new fears over safety of events.

LONDON — From London to Sochi to Rio de Janeiro, the deadly bomb attacks on the Boston Marathon raised new concerns Tuesday over safety at major sports events around the world, including the Olympics and World Cup.

The twin bombings near the marathon finish line that killed three people and injured more than 170 people brought into sharp focus the security challenges facing next year’s Winter Olympics in Sochi, Russia, the 2014 World Cup in Brazil and the 2016 Summer Games in Rio. “We are very, very concerned,” said senior IOC member Gerhard Heiberg of Norway. “Security is priority No. 1, no question about it.”

More immediate is the security planning for this weekend’s London Marathon, which attracts more than 30,000 runners and half a million spectators. Organizers said they were reviewing security for Sunday’s race — one of the world’s six major marathons — but the event will go ahead as scheduled in a display of unity with Boston.

“The best way for us to react is to push ahead with the marathon on Sunday, to get people on the streets and to celebrate it as we always do in London,” British Sports Minister Hugh Robertson said. “We are absolutely confident here that we can keep the event safe and secure ... The best way to show solidarity with Boston is to continue and send a very clear message to those responsible.”

Also taking place Sunday is the Bahrain Grand Prix, a Formula One race that faces its own security issues after a series of explosions, including a gas cylinder blast that set a car ablaze in the Gulf nation’s financial district.

IOC vice- president Thomas Bach, who was on his way to Sochi Tuesday for an international journalists’ conference, said the attacks in Boston reinforced the IOC’s policy that safety is paramount for any Olympics.

“I’m sure that this malicious attack will lead public authorities to have another look at all security measures,” Bach said.