Nick Clegg has called on Labour leader Ed Miliband to "rein in" Len McCluskey after the union leader called for civil disobedience during the Olympic Games.
The Deputy Prime Minister said he believed people would be "gobsmacked" and "appalled" by Mr McCluskey's call for the public to engage in civil disobedience to defend public services during the fortnight of sport this summer.
"I just think people will be gobsmacked, appalled, that someone thinks that at a time when we are finally hosting one of the greatest events in the world, he is calling for civil disobedience," he told ITV Daybreak.
"I know he is the sort of paymaster of the Labour Party but I hope Ed Miliband will rein him in."
Mr Clegg's remarks come after the Unite general secretary told The Guardian that trade unions could stage industrial action to disrupt the Olympic Games as part of their campaign against Government cuts.
Mr McCluskey said no precise plans have been drawn up for action during the London Games, but added that they "absolutely" could include strikes.
And he called on the public to engage in "civil disobedience" to defend public services during the fortnight of sport, which kicks off on July 27.
Conservative co-chairman Baroness Warsi said she was "shocked" by the Unite leader's comments. She called on Mr Miliband to "order" Mr McCluskey, who leads Britain's biggest trade union, to rule out disrupting the Olympics.
In the interview with The Guardian, Mr McCluskey was asked whether his union had discussed the possibility of strikes during the Olympics.
He replied: "Absolutely, yes.
"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.
"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."
Mr McCluskey said his union had not yet discussed "the specifics" of how workers could target the Olympics, but said that London bus drivers would be "examining what leverage points we have, and the Olympics will clearly come into play".
He added: "Now nobody has made any decisions yet and, of course, it would be nice if we were able not to disrupt such a prestigious event as the Olympics.
"But by the same token, people have to understand that we are fighting for our heritage here.
"Our parents and our grandparents, having defeated fascism in Europe, came back determined to build a land fit for heroes. They gave us the welfare state, the National Health Service, universal education.
"All of that is being attacked. I, for one, am not prepared to stand by and have my children or grandchildren say to me, 'What did you do when this was being taken away from us?'
"When you say what can we do, and the likes of the Olympics, I'm calling upon the general public to engage in civil disobedience."
Lady 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. Is it 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. Ed Miliband must urgently order his union cronies to rule out disrupting the Olympics."
Labour's Olympics spokeswoman Tessa Jowell said: "No one in our country looking forward to the Olympics, no athlete preparing, and none of our thousands of potential visitors, would understand or sympathise with any disruption to the Olympic Games.
"If this is a negotiation it should take place in private. Unions and employers should get together and sort it out without threats or disruption to Britain's Olympics."