David Cameron and Ed Miliband have both condemned a trade union leader's call for strikes and "civil disobedience" during the London Olympics as "unacceptable".
The Prime Minister and Labour leader were responding to comments made by Len McCluskey, who leads Britain's biggest union, Unite .
Mr McCluskey said workers should consider using strike action to disrupt the Games as part of their campaign against the Government's spending cuts.
The left-wing union leader told the Guardian attacks on public sector workers were "so deep and ideological" that targeting the Games would be justified.
"If the Olympics provide us with an opportunity, then that's exactly one that we should be looking at," he said.
"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. By then this crazy health and social care bill may have been passed, so we are looking at the privatisation of our National Health Service.
"I believe the unions, and the general community, have got every right to be out protesting."
Mr McCluskey said that, because of the seriousness of the issues at stake, he was encouraging the public to engage in "all forms of civil disobedience within the law" in the campaign against cuts.
The Prime Minister's official spokesman said the threat was "completely unacceptable and unpatriotic".
Also condemning the Unite boss, Conservative Party co-chairman Sayeeda Warsi said: "This is an appalling display of naked self-interest by Labour's biggest financial backer.
"The London Olympics will be a great occasion for this country. It is disgraceful for a trade union boss to be calling for mass disruption when the eyes of the world will be on Britain.
"I am shocked that Unite would sink so low as to spoil this great national event for everyone else."
She called on Mr Miliband to "urgently" order his "union cronies" to rule out such a move.
The Labour leader responded on Twitter, posting: "Any threat to the Olympics is totally unacceptable and wrong.
"This is a celebration for the whole country and must not be disrupted."
Deputy party leader Harriet Harman also criticised the proposal.
"I have spoken to Len McCluskey this morning and said that both Ed Miliband and I think he is wrong and we think that he shouldn't even have been floating the prospect.
"We all need to be rallying behind the Olympics.
"It is going to be an important opportunity for Britain and is going to affect our jobs, our economic growth in the future and the prosperity of this country," she said.
A senior Unite official told Sky News Mr McCluskey was not calling for industrial action specifically targeting the Olympics.
"There's no deliberate plan to disrupt the Olympics," she said. "But our members are feeling particularly aggrieved.
"Our members in London Transport are facing extra shifts and extra hours during the Olympics."
Bus drivers are calling for a £500 Olympics bonus to match that offered to Tube drivers, but talks have broken down and there could be industrial action as a result, the official said.