- 33 updates
The London Marathon, registration and all associated events will go ahead as originally planned, organisers said.
Security arrangements will continued to be reviewed in partnership with the Metropolitan Police and other authorities.
London Mayor Boris Johnson said that in London "police will be taking every possible precaution" to make sure that the London Marathon and Margaret Thatcher's funeral can go ahead as planned.
Sports Minister Hugh Robertson said he was as "confident as you possibly can be at this stage that we will deliver a safe and secure" London Marathon on Sunday.
Prince Harry will attend the London Marathon this weekend despite the explosions at the Boston Marathon.
The royal, who is patron of the London Marathon Charitable Trust, will still will make the presentations to the winners of the various races including the elite men and women events.
He will also meet a selection of volunteers involved with the running of the annual event and members of the St John Ambulance.
A St James's Palace spokesman confirmed that the prince would be attending the marathon as planned but declined to comment further, he said: "As far as we're concerned there's nothing to suggest any change."
Some 347 of the 25,000 taking part in the race were British and several told of the aftermath of the two blasts.
Mike Kendall, from Northampton, tweeted after completing the 26.2 mile race:
Anthony Meenaghan, 21, an architectural technology student from Sheffield Hallam University who is on a work placement in Boston, tweeted
Sports minister Hugh Robertson insisted he was "absolutely confident" that the London Marathon could be kept safe.
Asked if he believed it should still go ahead, he told the BBC Radio 4 Today programme: "Yes, I do.
"These are balance of judgements but we are absolutely confident here that we can keep the event safe and secure.
"I think this is one of those incidents where the best way to show solidarity with Boston is to continue and send a very clear message to those responsible."
An email sent to people taking part in Sunday's London Marathon told competitors that organisers "fully expect" that the race will go ahead.
It added that race security was being reviewed in conjunction with the Metropolitan Police.
The chief executive of the London Marathon said security for Sunday's race will be reviewed with the Met Police in light of the explosions in Boston.
Nick Bitel said that as more information as to what actually happened in Boston comes in, race organisers and police will adjust security to meet any "threat assessment".
Mr Bitel said: "The London Marathon has a security plan which is developed in conjunction with Metropolitan Police.
"As soon as this new broke we were in contact with our colleagues from the Met, and we will be reviewing our security in the coming days, in the light of what has happened in Boston, and as more information comes out of that city as to what has actually occurred.
"I don't want to talk about specifics of what security we have had in the past, or will have on Sunday. All I can say is that it will be of an appropriate level to meet whatever threat assessment is made, in conjunction with the Met police."