Douglas Alexander MP, Labour's Shadow Work and Pensions Secretary, said:
"We support the underlying principle of simplifying the benefits system and providing real incentives to work.
"My concern is that George Osborne's recent actions reveal he doesn't support these principles - he has already both complicated the system and undermined incentives to work through changes such as the reduction in working tax credit.
“Some of the key aspects of Iain Duncan Smith’s original plan already seem to have been cut and that could mean some people facing bigger barriers to getting back to work.
"And our overriding concern is that there is a fatal flaw at the heart of these proposals - without work they won't work."