David Cameron was told that he should be "ashamed of himself" as he was heckled by an official London 2012 volunteer during a speech to mark the month-to-go countdown to the start of the Olympics.
The Prime Minister was making a speech to about 200 Games Maker volunteers at a specially-arranged visit to the official uniform distribution centre in east London when the protester stepped forward.
Just 22 seconds into Mr Cameron's speech, the protester, dressed in the purple and orange official uniform, shouted: "Shame on you, David Cameron - you are crippling the poor in London. Shame on you..."
The man tried to continue to speak but his words were drowned out by the other volunteers.
He was then quickly ushered out of the room.
Mr Cameron, who was standing on a podium, responded by saying: "This is not about politics. This is about Britain. It is about volunteering. It is about our country. It is about a successful Olympics."
A London 2012 spokesman said: "People are allowed their political views.
"It was just a rather inappropriate place and time to air them."
No further information was given on the volunteer but London 2012 said he would continue in his role.
The heckling came after it was announced by Mr Cameron that Housing Benefit for the under 25s could be scrapped.
The embarrassing episode happened after London 2012 chairman Lord Coe was greeted with a standing ovation and a warm round of applause when he stepped into the room. He thanked the volunteers for their hard work.
Mr Cameron received the same reaction during the surprise visit before the intervention. The incident lasted a few minutes.
There are 70,000 Games Makers who have been signed up to work at the Olympics.
They are seen as the welcoming face of the Games and will be spotted doing anything from greeting visitors to transporting athletes, helping out behind the scenes and working with the technology team to ensure the results get displayed quickly and accurately.
The centre, which also hands out kit and accreditation to staff and contractors, has so far issued 40,000 uniforms.
It will process about 2,000 to 2,500 people a day.
Mr Cameron said it was "staggering" that 250,000 people had tried to become a volunteer.
He told them: "Coming here today and seeing what you are doing really brings it home to me what an enormous amount you are giving up to be part of these Games.
"These Games could not exist without you - so a really big thank you.
"You are going to work really hard over these next few weeks. Some of you have been working really hard already so a really big thank you on behalf of the whole country for what you are about to do.
"You will not just be part of the Games. You will be what makes the Games a success.
"The people who come to the Games, the visitors, the athletes, the foreign leaders, - what you do will make a real difference between a successful Games and an absolutely fantastically successful Games.
"Please give it your all to give everybody an incredibly warm welcome.
"One of the best bits of legacy we can give our country is the inspiration that all of you provide by volunteering to take part in the Games in the first place.
"I think people will look at your example and think 'What more can I do to help build a stronger society and a stronger country?'."
Lord Coe, a two-time Olympic 1500m champion, told the volunteers: "I am very lucky. I have competed in two Olympic Games. I have been a worker at about five others.
"Everyone of those optics I have seen the Games through, I can tell you that you are the guys that make the difference between a good and a great Games.
"It is you who will be in the memories of people that leave our country. You turn the lights on and you turn the lights off at the end of competition. Thank you for being here."
Earlier Mr Cameron rolled up his sleeves to help hand out some of the uniforms.
A stunned Mairead McMahon, 19, of Lurgan, Northern Ireland, had already excitedly telephoned her mother Anne at home to say she could see Lord Coe when Mr Cameron handed her a polo shirt.
Ms McMahon, who will be working at Wembley Arena during the Olympics, said picking up her uniform would now be one of her "big-time memories" of working at London 2012.
She said: "I have never been out of Ireland. This is my first time of going anywhere on my own. I thought I was going to come and get my uniform and then, bang, Seb Coe and David Cameron were there.
"Today it really did sink in. Coming and seeing everybody in their hundreds, if not thousands, shows it is going to be just amazing."