The Work and Pensions Secretary Iain Duncan-Smith says it is "madness" that taxpayers are supporting families with large numbers of children to live on benefits.
Campaigners are worried capping welfare payments for big families will push more children into poverty.
But Iain Duncan-Smith told the Today presenter John Humphrys that it is about "fairness".
Benefit changes are "not about penalising people", he explained, "Benefits should be
a temporary place."
"Universal credit... massively attacks that problem of in-work poverty," he added.
Get in touch with Today via
or text us on 84844.