MSPs are calling for a stop to the next stage in the rollout of universal credit over fears about the impact it will have.
The next phase of the new benefit's implementation is due to start in Yorkshire this month.
For the first time it involves people on existing benefits being moved to universal credit.
One MSP warned the scheme had been "littered with mistakes" since being introduced in 2013.
MSPs on the Scottish Parliament's social security committee have told the UK government they want more clarity around the impact the move will have on those affected.
In March, Work and Pensions Secretary Amber Rudd confirmed claimants in Harrogate who still receive the old-style benefits will be the first people to be moved to universal credit under a pilot scheme starting this month.
The benefit was previously introduced gradually across the country for people making new claims.
Committee convener, SNP MSP Bob Doris, warned the scheme was not working and said the pilot scheme should be stopped.
He said: "We are deeply concerned that despite raising this issue as part of the committee's In-Work Poverty Inquiry with the DWP in January, and the UK government's failure to appear at our committee to give evidence, they have carried on with plans for implementation regardless."
He added: "This movement represents a huge cultural shift and we do not believe it is right to sanction the working poor, effectively punishing people for going to their work.
"The DWP has said they are currently taking a 'light touch' approach to in-work conditionality or sanctions but there is little confidence that when the system rolls out more widely that low paid and part-time workers won't suffer as a result.
"The rollout of universal credit has been littered with mistakes and it is vital that this latest pilot is put on hold to ensure that there is no negative impact upon claimants who rely on this money."
The committee has also stated its opposition in principle to attaching punitive conditions to those already in work.
Speaking at the time of the announcement of the pilot in March, Amber Rudd said: "Moving people from the old and outdated benefits system to universal credit is a positive and important moment.
"Once on universal credit people will benefit from a more personal service and can expect to receive up to six benefits combined into one, making it easier for them to manage their money.
"But the switch needs to be done carefully which is why we are taking a step-by-step approach to this, starting in Harrogate.
"I want to be sure that the switch to universal credit is a hassle-free process for claimants and everyone receives the personalised service they deserve."
A DWP spokesperson said: "We are taking a measured approach to moving people to universal credit from the old system, working with expert stakeholders to ensure vulnerable and complex claimants are fully supported.
"We will also consult with Parliament before extending the process to more people."