Most people who become unemployed will soon have to wait weeks before they get any benefit payments, according to a new report.
The TUC said small print in Universal Credit rules disclosed that people losing their jobs will not be eligible for any help for a week, and will then have to wait a further month for their benefits.
The union organisation said it was a "new and deliberate delay" which could distract new claimants from looking for work and drive them into the hands of payday loan firms.
The report, published ahead of the latest unemployment figures, said the new five-week wait will apply to anyone making a fresh claim for social security benefits.
The TUC launched a campaign against the Government's welfare reforms, saying a poll of more than 1,600 adults showed that most were opposed to a five-week wait.
TUC general secretary Frances O'Grady said: "While it is right to deal with people who abuse the system, the Government is now undermining the welfare safety net that any of us might need. Making people who have contributed all their lives - but who are simply unlucky enough to lose their jobs - wait five weeks before receiving any help is both cruel and vindictive.
"Just as with the bedroom tax, it shows that ministers are desperately out of touch with the lives of ordinary people, many of whom do not have any savings to fall back on.
"People who lose their jobs need to be concentrating on looking for a new one, not worrying about whether they have enough money to pay the mortgage, keep up with their rent or feed their children.
"We already know that Universal Credit is way over budget and in the intensive care ward. The five-week wait is yet another ill-thought out idea and should be enough to send the whole policy back to the drawing board."
A separate report by the Recruitment and Employment Confederation showed that over a third of people had worked as a contractor, freelancer or for an agency.
A survey of more than 4,200 adults found that one in four had been a temporary agency worker at some point in their career.
Chief executive Kevin Green said temporary work was regarded as a second rate career, but he argued it was valuable for people with family commitments or wanted to learn specific skills.
A Department for Work and Pensions spokesman said: "Universal Credit is a vital reform that will simplify the benefits system and make work pay.
"The seven day waiting period for benefits is not limited to Universal Credit but will apply to out-of-work benefits under the current system too. People can apply for an advanced benefit payment if needed.
"Paying benefits monthly is an important part of Universal Credit because it replicates the world of work and makes the transition to employment much smoother. We have matched this with increased budgeting support."