David Cameron: 'Families will be £2,400 a year better off'

David Cameron has said some families will be £2,400 a year better off under reforms announced by the Conservatives.

It comes amid a row over plans to curb tax credits for million of workers.

Ministers have said the £30bn spent a year on tax credits - paid to those in work at the lower end of the income scale - is unsustainable.

Speaking to Newsnight the prime minister insisted the changes would make the economy stronger.