The Prime Minister's spokesman said that a Twitter error that saw David Cameron link to an account spoofing Iain Duncan Smith was 'one to take on the chin'.
The Taxpayers' Alliance have supported the Government's new benefits cap which is being introduced across Britain today, saying it is "fair" to both taxpayers and benefits recipients.
Matthew Sinclair, chief executive of the charity, said: "The people funding the benefits system through their taxes should never find themselves subsidising a lifestyle for others which they cannot afford for their own families."
"Ministers are right to be simplifying the benefits system and removing the perverse incentives that have condemned people to a life on hand-outs."
British Children will "pay the price" for the Government's new benefits cap with parents having less to spend on food, clothes and rent, according to a children's charity.
Matthew Reed, chief executive of the Children's Society, said it was not right for the government to try and make work pay by "putting children on the breadline":
The charity called on the government to do more to tackle sky high rents in some areas of the UK as well to make childcare affordable.
David Cameron has unwittingly cited an Iain Duncan Smith parody account in a tweet championing the Government's benefits cap roll-out.
The Prime Minister announced he was working with @IDS_MP - a Twitter user who exclaims "Chin chin old bean" in his profile bio.
Other tweets from @IDS_MP lament the rising cost of foie gras and predict that working class children will grow up to become drug dealers.
Work and Pensions Secretary Iain Duncan Smith has defended the new benefits cap of £500 a week, arguing that it is necessary to change a culture of large families staying out of work.
"This is both about saving money and, more particularly, about changing a culture that had left families, particularly large families, finding it easy and a reality for their lives to stay out of work on taxpayers' benefits," he told BBC Breakfast.
The MP said a "very, very significant number" of people had gone out to work in households within the four London boroughs where the cap has been trialed.
Smith added: "The key principle behind this all over the country is that those who work, those who are trying to do the best in their households, do not see others who are down the road, who are on benefits, on welfare, actually getting more than they do."
A limit on the total amount of benefits that people aged 16 to 64 can receive has begun rolling out across England, Scotland and Wales.
The cap, which applies to people receiving jobseeker's allowance, child benefit, child tax credits and housing benefit, will see couples and single parents receive a maximum of £500 while single people will only receive £350.
The benefits cap, which is said to reflect the average household income, has already been rolled out in four London boroughs and will be fully implemented by 30 September.
The government's huge shake-up of the benefits system came into effect for a trial run today.
The controversial "benefits cap", in which families can receive no more than £500 a week in state handouts, is being piloted in four London boroughs ahead of its national launch.
The Government say it is an incentive to work, but critics claim it will penalise families in need.
ITV News reporter Sejal Karia has more:
Labour leader Ed Miliband said the benefits cap should take into account housing costs in each region.
"We've said we're in favour of a benefit cap but it has got to be adjusted regionally depending on housing costs in each region," he said.
"The danger of the way the government is doing the cap is that it forces people into temporary accommodation, bed and breakfast accommodation, which drives up costs, not reduces them.
"And actually what we're seeing with the welfare bill is, despite the cuts the government is making, the welfare bill rising and not falling."
Kate Bell, from the Child Poverty Action Group, said rising rent costs in London would mean the benefit cap hits families in the capital extra hard.
"We don't think it's fair to make children suffer for this cap.
"The real reason why people are going to be hit by the cap is because of the cost of their housing - most of the money these people are receiving in state support is going to housing benefit, which, of course, goes to the landlord, not to the family."
Claimants in the London boroughs of Haringey, Enfield, Croydon and Bromley are the first to face a cap on their benefits.
Employment minister Mark Hoban said it was "only fair that those who are on benefit face the same choices" as those in work.
But shadow minister for disabled people Anne McGuire highlighted the "major issue of imposing that level of benefit cap in London, where the biggest factor in benefits is actually the high rents."
Political correspondent Libby Weiner reports: