Welfare Reform Minister Lord Freud has issued a "full and unreserved apology" after suggesting that some disabled people are "not worth" the minimum wage - but stopped short of resigning.
The Tory peer said he had been "foolish" in "accepting the premise" of a question posed to him during a fringe event at the Conservative Party conference last month.
The views expressed by Conservative Lord Freud relating to the wages of disabled workers are "completely unacceptable", the Liberal Democrats said.
A party spokesman said: "The views expressed by Lord Freud are completely unacceptable.
"The Liberal Democrats are proud to have raised the minimum wage repeatedly in Government and will resist any attempt to cut it for anybody, not least the disabled."
But the party said it for the Prime Minister David Cameron to decide whether the welfare minister should resign.
"Conservative ministerial appointments are a matter for the Prime Minister," the spokesperson said.
Questions to be asked over meaning behind Lord Freud's comments relating to disabled workers.
Ed Miliband has called for Tory Lord Freud to resign after he suggested some disabled workers are 'not worth' the full minimum wage