Unemployment could be as high as 6.3 million in the UK if a different counting measure was used, highlighting the true scale of joblessness, according to a new report.
The TUC said the higher figure - more than twice the official total - was revealed using an American measure, which includes people in part-time jobs because they cannot find full-time work and recent redundancies.
The jobless total increased to 2.68 million last month and is expected to rise again when new figures are published by the Office for National Statistics on Wednesday. However the TUC study suggested the actual number of unemployed people in the UK could be 6.3 million, the most since the early 1990s.
Under-employment, which counts those doing temporary or part-time jobs because they cannot find permanent, full-time work, has risen to a record 1.9 million, it said. The TUC said temporary jobs were better than unemployment, but tended to be low paid, insecure and offered little or no career prospects.
TUC general secretary Brendan Barber said: "The headline unemployment figures are bad enough, but the true scale of joblessness is even worse. Over six million people are either out of work or under-employed. Tackling this crisis should be the Government's number one priority.
"Our jobs crisis is not confined to those out of work. Nearly two million people are being forced to take low-paid, insecure, short hours jobs because of the lack of proper full-time employment. This means people are taking home much less pay, which is putting a real strain on family budgets.
"When ministers say there are plenty of jobs out there, they are ignoring the sheer numbers of people looking for work, as well as the suitability and location of the jobs available. Rather than seek to blame unemployed people for being out of work, the Government should start helping them by putting proper resources into employment schemes."
The report followed a study by the Chartered Institute of Personnel and Development which showed that job prospects are set to worsen in the coming months as firms make workers redundant. A survey of 1,000 employers also revealed a further widening of a North-South divide in the jobs market.
A Department for Work and Pensions spokeswoman said: "Tackling unemployment is a priority for ministers, which was why the Government acted quickly to replace the numerous failing back to work schemes with the Work Programme."
Shadow work and pensions secretary Liam Byrne said: "This analysis shows the true scale of our country's unemployment emergency, yet still complacent ministers are failing to act."