Iain Duncan Smith has said he is "delighted" at being given the opportunity to finish his controversial welfare reforms. 

The The Chingford and Woodford Green MP's re-appointment as Work and Pensions Secretary was among the first to be announced today by David Cameron.

Duncan Smith will now be responsible for completing the roll-out of Universal Credit, which integrates six benefits into one, and overseeing £12bn worth of cuts to the welfare budget by 2017-18.

Details of the next wave of cuts are yet to be outlined, although a department for work and pensions document leaked in March suggested savings could be made by reducing benefits paid outside of London, taxing disability allowances and scrapping a carers allowance - except to those on the lowest income. 

The Tories at the time insisted the proposals were not party policy. 

Reforms already introduced by the previous coalition included freezes on many benefit payments, the removal of child benefit from better-off families and a £26,000 annual household benefit cap.

The reforms have brought sharp criticism from opposition parties, campaigners and charities, who say they push people further into poverty.

David Cameron has rejected proposals to limit child benefit to two children. 

Duncan Smith said: "It is a privilege to serve in the government, and I am delighted to have the opportunity to complete the vital welfare reforms that have already helped so many people back into work.

"The completion of Universal Credit will ensure work always pays, and will improve the incomes of those on low salaries.

"We have made real progress, but the job’s not done.

"I’m delighted to have the opportunity to finish it."

On polling day, the former party leader told the Guardian he did not believe his welfare reforms had affected his popularity in the constituency as "most people understand the need to reform welfare."

His majority fell by 11 per cent from the 2010 election.