The UK Employment Minister is "insulting" welfare claimants by refusing to give evidence to MSPs about benefits sanctions, the convener of a Holyrood committee has said.
Members of the Scottish Parliament's Welfare Reform Committee had hoped to question Esther McVey on the issue next month.
But the Conservative told them as social security was a reserved issue, she was accountable "first and foremost to the UK Government and Parliament".
Ms McVey wrote to the committee to state she would be "more than happy" to meet them informally to discuss the issue of benefits sanctions.
Committee convener Michael McMahon told her that was "disappointing", adding that this "follows a number of previous invitations to UK ministers to formally provide evidence to the committee which have all been declined".
Work and Pensions Secretary Iain Duncan Smith and Welfare Minister Lord Freud have both previously refused to give evidence to the committee.
Mr McMahon said: "UK ministers from other policy areas have been to Holyrood and assisted the work of the Scottish Parliament.
"It seems the exception to this positive relationship is welfare reform, since Esther McVey has sadly chosen to join Iain Duncan Smith and Lord Freud in refusing to give evidence to us in public. The UK Government is consistent in its inconsistency on this policy matter.
"Worse than this though, her refusal is insulting to the individuals who have taken the time to come here and talk to us about the details of their daily struggles, often at the expense of their own health."
The Labour MSP added: "We still have an invitation out to the Secretary of State for Scotland Alastair Carmichael MP.
"Perhaps he will be able to speak to us publicly about the policy impacting negatively on so many Scots."
Mr McMahon spoke out ahead of a Holyrood debate on the impact of welfare changes brought in by the UK Government last April, including the so-called bedroom tax.
Committee deputy convener Jamie Hepburn called on Ms McVey to "watch our debate today to hear about the impact of the reforms on the ground that MSPs are dealing with every day in their constituencies".
Mr Hepburn also criticised Ms McVey for not giving evidence to the committee, saying that she "has time to address an expensive conference in a four-star Edinburgh hotel on the subject yet feels there is no imperative for her to give evidence to our committee".
The SNP MSP added: "In the past few months, the Secretary of State for Scotland Alastair Carmichael MP has given evidence to the Health and Sport Committee on child poverty and Chief Secretary to the Treasury Danny Alexander MP has given evidence to our Finance Committee and Economy, Energy and Tourism Committee. All in public.
"It seems the UK Government is happy to give evidence on the record at Holyrood unless it is about welfare reform. That silence speaks volumes."
Mr McMahon said as the committee were "keen to pursue discussions" on the Department for Work and Pensions (DWP) policy on sanctions, MSPs would accept Ms McVey's offer of an informal meeting.
Meanwhile, arrangements will be made for a senior official from the DWP to give formal evidence to the committee.
A DWP spokeswoman said: "Ministers already appear in front of UK Select Committees as social security is a UK matter. In addition, ministers have offered to meet with the Scottish committee in an informal capacity."