- 17 updates
The Prime Minister said "wider questions" had been raised about the welfare system.
ITV News Political Correspondent Libby Wiener reports:
Senior Liberal Democrats have not entered the row which has seen David Cameron back Chancellor George Osborne's comments that the case prompted "wider questions about our welfare system."
Mr Alexander said: "The Philpott case is an individual tragedy. Children have died in that case.
"I think that is where we should let that case lie. I would not want to connect that to the much wider need to reform our welfare system."
The Prime Minister agreed with the Chancellor that the Philpott case prompted "wider questions about our welfare system".
The Prime Minister said the Chancellor's remarks about the Philpott case "were absolutely right".
He said: "I think what George Osborne said was absolutely right.
"He said that Mr Philpott was the one to blame for his crimes and he should be held responsible but what the Chancellor went on to say is we should ask some wider questions about our welfare system - how much it costs and the signals that it sends.
"We do want to make clear that welfare is there to help people who work hard, it shouldn't be there as a lifestyle choice and I think that's entirely legitimate."
Conservative Party chairman Grant Shapps denied the Chancellor was exploiting the deaths of the six Philpott children for party-political advantage by linking them to the welfare debate.
Shadow Chancellor Ed Balls launched a scathing attack tonight on what he called the "cynical, nasty and divisive" way George Osborne linked the Philpott case with the broader issue of state benefits.
Mr Balls said the "desperate" Chancellor had offended millions of hard-working people and was playing politics with a tragic case for his own political gain.
The shadow chancellor Ed Balls has condemned the "nasty and divisive" comments by George Osborne in which he questions why taxpayers' money was being used to "subsidise lifestyles" like Mick Philpott:
Latest ITV News reports
David Cameron has backed Chancellor George Osborne after he linked the Mick Philpott case with the welfare system.