A warning by David Cameron for the House of Lords not to try to block the UK Government’s financial plans has gone unheeded after the Liberal Democrats said they planned to table a motion in the Upper Chamber to kill off its proposals for £4.5 billion of tax credit cuts.

If approved by peers next week, the so-called "fatal motion" being tabled by Baroness Manzoor, the Lib Dems’ Work and Pensions spokeswoman, would force Ministers to come back with a revised version of their proposals, due to be implemented in April.

At Commons Question-time, the Prime Minister warned: "This House has now decided twice in favour of this measure; once when voting on the statutory instrument and again last night in a vote put forward by the Opposition.

"The House of Lords should listen to that very carefully and recognise that it's for this House to make financial decisions and for the other House to revise other legislation."

Mr Cameron gave no details of what action could follow an adverse vote in the Lords after Conservative backbencher Jacob Rees-Mogg suggested it would "entitle him to review the decisions of Grey and Asquith in relation to creating more peers to ensure the Government can get its financial business through".

The PM faced a barrage of questions on the issue with Labour leader Jeremy Corbyn among those seizing on the decision by Tory backbencher Heidi Allen to use her maiden Commons speech to warn the tax credit cuts went "too hard and too fast".

Later, senior Tory Sir Edward Leigh on a Point of Order noted how it was “elected representatives of the people, who decide on tax and spending” and asked the Speaker: “In your discussions with the Lord Speaker…will you make it clear that it is not for the unelected House of Lords to determine tax and spend?”

In response and in what appeared also to be a warning shot to the Lords, John Bercow said: “In the final analysis, each House knows what the factual constitutional position is and that position is…of long-standing.”

But Lady Manzoor rejected the argument that the tax credit cuts were covered by parliamentary convention barring the Upper House from blocking financial measures passed by the Commons.

"The House of Lords has the absolute constitutional right to oppose measures that it believes are flawed or damaging. I can think of few better reasons to use this power than to stop moves to cut vital support for millions of working families."