The British government said Monday that it would no longer pay a universal child subsidy to wealthier families, opening a campaign that may end up transforming Britain’s welfare system by reducing benefits to the middle and upper classes.

The decision, announced by George Osborne, the chancellor of the Exchequer, at the Conservative Party conference in Birmingham, departs from the Tory campaign promise to not place income restrictions on this hugely popular benefit and represents perhaps the most direct attack yet on the rich menu of broad-based entitlements that have underpinned European welfare states.

The government is scheduled to disclose on Oct. 20 how it intends to cut about $130 billion in spending over the next four years, cuts intended to sharply narrow a budget deficit that, at 11 percent of GDP, is one of the biggest in the world.

In his speech, Osborne, whose job is the equivalent of a finance minister, said that as of 2013, families making $70,000 a year would not qualify for the benefit, which pays $32 a week for a first child and $21 for each subsequent one.

“A system that taxes working people at higher rates only to give it back in child benefits is very difficult to justify at a time like this,” Osborne said. “We have got to be tough but fair, and that’s why we will withdraw child benefit from households with a higher-rate taxpayer.”

The government estimated that 1.2 million families, or about 15 percent of the total, would no longer receive the payments.

At roughly $310 billion a year, overall welfare spending, known here as social protection, is the largest component of the British budget. Since the government has ring-fenced the next largest spending category, health care, and is under pressure from the conservative wing not to cut military spending as much as initially suggested, it has been forced to retreat from its campaign promises to protect the middle class from such cuts.

To be sure, the $1.6 billion in savings is a tiny part of the overall deficit, but symbolically it carries much greater weight by suggesting that other universal benefits that have disproportionately benefited the middle class, including heating allowances, free bus passes and television licenses for the elderly, might also be vulnerable.

The government’s decision to single out middle-class families is also likely to resonate in other debt-plagued economies in Europe, particularly Ireland’s.

The Irish government, having just devoted the equivalent of 30 percent of its GDP to bailing out its devastated banks, is again under severe pressure to cut spending further. Like Britain, Ireland pays a benefit to families with children, one that may be even more generous than Britain’s. On Monday, the Irish minister for children said he could not rule out cuts in child benefits.

And in Iceland, another country grappling with a mountain of debt, politicians are saying that child benefits for higher-earning families are likely to be trimmed in the next budget.