The British minister of sport has confirmed the London Marathon will go ahead as planned this Sunday, despite the bomb attack on the Boston race, which killed three people and wounded at least 144 others.

"The best way for us to react is to push ahead with the marathon, to send a very clear message that we won’t be cowered by this sort of behaviour," Hugh Robertson told the BBC on Tuesday.

The minister also said officials are confident that organizers of the London event will be able to "deliver a safe and secure marathon."

About 37,000 runners are expected to run the 42-kilometre race, starting at Greenwich Park and ending at the Mall.

An estimated 500,000 spectators are expected to line the streets to watch the marathon.

The London marathon's chief executive Nick Bitel said organizers would not be "complacent" and would look at security arrangements again in case more is needed to be done.

London Mayor Boris Johnson told Reuters he has talked with the city's police commissioner about both the race and the funeral of former prime minister Margaret Thatcher, which is scheduled to take place Wednesday.

"We have got the funeral, and then obviously we have got the marathon at the weekend," Johnson told the news agency. "Clearly we will be calling on the public to be vigilant, and maybe there will be some intensified search operation but certainly we will be proceeding as normal."

With files from The Associated Press