Downing Street has denounced a union leader's threat of strikes to disrupt the Olympics as "completely unacceptable and unpatriotic".
Len McCluskey, general secretary of Unite, told The Guardian that unions could stage industrial action as part of their campaign against Government cuts.
He called for the public to engage in civil disobedience to defend public services during the fortnight of sport this summer.
Mr McCluskey said no precise plans had been drawn up for action during the London Games, but added that they "absolutely" could include strikes.
"The attacks that are being launched on public sector workers at the moment are so deep and ideological that the idea the world should arrive in London and have these wonderful Olympic Games as though everything is nice and rosy in the garden is unthinkable. Our very way of life is being attacked," he said.
"I believe the unions, and the general community, have got every right to be out protesting. If the Olympics provide us with an opportunity, then that's exactly one that we should be looking at."
Responding to his comments, Prime Minister David Cameron's official spokesman said: "The Olympics are a great opportunity for this country to show everything that is great about the United Kingdom and advertise ourselves to the world.
"It is completely unacceptable and unpatriotic what he is proposing. Most people in this country, including members of that union, think the Olympics is a great occasion for the country and wouldn't want to see anything happen that would disrupt it in any way."
Mr McCluskey's comments were also condemned by Labour leader Ed Miliband, whose party is largely funded by union donations.
"Any threat to the Olympics is totally unacceptable and wrong," said Mr Miliband. "This is a celebration for the whole country and must not be disrupted."