Iain Duncan Smith has lashed out at EU Employment Commissioner Laszlo Andor after he warned that the UK government's benefits restrictions looked "nasty".
The work and pensions secretary wrote to Andor, who previously urged ministers to "think twice" about limiting benefits for EU migrants, accusing him of bias against Britain.
Andor had also said the government's Youth Contract was "not sufficient to deliver" progress in tackling youth unemployment.
Duncan Smith pointed out that the UK has the second highest youth employment rate of the major EU economies, adding: “Singling out the UK for criticism gives me the impression that the Commission is not capable of impartial analysis and comment."
The war of words comes as a report by Oxfam and the New Policy Institute warned that benefit cuts had left up to 200,000 families £18-a-week worse off and pushed 1.75 million people deeper into poverty.
The report found that 300,000 families had suffered a cut in housing benefit, 920,000 in council tax support and 480,000 in both benefits.
Oxfam chief Mark Goldring said that the coalition was “blowing massive holes in the safety net which is supposed to stop people falling further into poverty”.
He added: “We are already seeing people turning to food banks and struggling with rent, council tax, childcare and travel costs to job centres."
EU employment commissioner Laszlo Andor warned in February that the coalition should "think twice" about cutting benefits for EU migrants as he warned it could spark "conflict".
Andor said the new rules, which mean EU migrants have to show they are earning at least £149 a week for three months to be eligible for benefits, would cause "difficulties".
"I believe we will have some difficulties because workers in the European Union have rights," he told BBC Radio 4's Today programme.
"This is something you have to understand and you cannot judge the working status of somebody after the level of earning. The case law in the European Union actually points to the opposite direction.
"What I understand is that in the last few months some members of the British government did not really mind that what they say is confronting the principles in the legislation of the European Union.
"Government should think twice before launching such new initiatives because, unfortunately, that can lead to a kind of conflict."
Asked if that meant it would be challenged, he replied: "First we need to see in writing what the new system will be and after we can make a conclusion."
He told the programme: "There is so much in the tabloid newspapers about Romanians and Bulgarians that people probably believe that there is a kind of influx while in reality the Romanians and Bulgarians are just a minority among the so-called EU migrants.
"The EU migrants, those coming from other EU countries to the UK in the last 20 years, never came up to the half of total immigration, so what exactly is the problem and what exactly can be remedied by tinkering with the rules, and the rights and the entitlements of EU citizens should be explained in a more factual way rather than just responding to gut feelings."
A Department for Work and Pensions spokesperson said: “Britain has a strong welfare state, but for too long the system trapped those it was designed to help in a state of dependency. There’s nothing kind or fair about that.
“That’s why the Government is fixing the system. Work is the best route out of poverty so we’re making sure it pays to work and supporting people into employment - with an extra 1.5 million people in work since 2010.
“We’re making the system fair to claimants and to taxpayers, and a strong safety net remains. We spend £94 billion a year on welfare for working-age people so those on low incomes or looking for work can meet their basic needs.
“Our reforms are specifically designed to improve the lives of the poorest in our society - with three million families better off as a result of Universal Credit.”
See also: Iain Duncan Smith's £53 week