LONDON (Reuters) - A senior MP who resigned on Friday said vulnerable working age people were unfairly carrying the burden of deficit reduction, belying the prime minister’s claim that austerity was being shared by all.

Britain's former Secretary for Work and Pensions, Iain Duncan Smith, arrives for a television interview in central London, Britain March 20, 2016. REUTERS/Neil Hall

Iain Duncan Smith, who quit his post of work and pensions secretary over changes to disability welfare payments, said he had come under “massive pressure” to cut welfare budgets as part of a “desperate search for savings” ahead of Chancellor George Osborne’s budget statement last week.

Duncan Smith denied speculation that his resignation was triggered by his position on Europe, where his desire for Britain to leave the European Union pits him against Prime Minister David Cameron and Osborne.

He told the BBC that juxtaposing welfare changes against tax cuts for the wealthy in the budget was damaging to Cameron’s Conservative party and to the country.

“That is deeply unfair and was perceived to be unfair,” he said in his first interview since he resigned.

“And that unfairness is damaging to the government, it’s damaging to the party and it’s actually damaging to the country,” he said on Sunday.

Cameron and Osborne’s flagship policy of reducing Britain’s budget deficit was being pursued at the expense of some of the poorest in society, he said.

“(The government) has become too focussed on narrowly getting the deficit down without being able to say where that should fall other than simply on those who I think can less afford to have that fall on them,” he said on the Andrew Marr show.

“I think it is in danger of drifting in a direction that divides society rather than unites it, and that I think is unfair.”

He said he considered resigning a year ago, and had felt increasingly “isolated” in a government “losing the narrative that the Conservative Party was this one nation party caring for those who don’t even necessarily vote for it”.

Energy Secretary Amber Rudd told Sky News on Sunday that she was “perplexed” by the move, echoing comments made by Cameron on Friday, who was “puzzled and disappointed” by Duncan Smith’s decision to leave the Cabinet post he has held since 2010.

(This version of the story corrects spelling of Smith’s first name to “Iain” from “Ian” in second paragraph).