The mayor of London, Boris Johnson, has hit out at American presidential candidate Mitt Romney for comments suggesting Britain is not ready to stage the Olympic Games.
Mr Johnson fired up a large crowd in Hyde Park, saying: "There's a guy called Mitt Romney who wants to know whether we're ready. Are we ready? Are we ready? Yes, we are!"
Mr Romney, a Republican who will take on President Barack Obama in November's election, made his remarks on the first official day of a week-long tour that is to include stops in Israel and Poland.
The BBC reports that in the contest for the Republican nomination, he made much of the fact that he delivered a successful Winter Olympics in Salt Lake City in 2002, when he was chief executive of the event.
Interviewed by the US network NBC on Thursday, he said London's difficulties with security guards and threats of border staff strikes were "obviously...not something which is encouraging".
"It's hard to know just how well it will turn out," he added.
At the end of a day during which the Olympic torch made its way one last time through the streets of London, those remarks brought a caustic reaction from Mr Johnson in front of a huge sun-baked crowd in Hyde Park.
Tone moderated after meeting PM
They also prompted a response from prime minister David Cameron, who praised London's readiness and said it would be easier to organise an Olympic Games "in the middle of nowhere" - a remark widely seen as a reference to the 2002 winter Games.
After meeting Mr Cameron for talks, however, Mr Romney said mistakes were to be expected and he was sure the London Games would be a success.
Back in the US, Romney supporters insisted the day's events were not relevant to the presidential race. Yet the back-and-forth attracted attention on Twitter, and did dominate US television coverage of Mr Romney's day in London.
He will attend the opening ceremonies of the Olympic Games before departing for Israel.