UK unemployment rose by 49,000 to almost 2.5 million in the three months to the end of November, the Office for National Statistics (ONS) has said.
One in five 16 to 24-year-olds are now out of work, after a rise of 32,000 to 951,000 without jobs, the highest figure since records began in 1992.
The UK unemployment rate is 7.9%, but for 16 to 24-year-olds it is 20.3%.
Prime Minister David Cameron said any rise in unemployment was a "huge concern".
He added that there were some "very disappointing" figures, particularly on youth unemployment.
Labour leader Ed Miliband accused Mr Cameron of "complacency".
Referring to the government's spending cuts and the impact on public sector jobs, he added: "The truth is you are cutting too far and too fast and it is British people who are paying the price."
Other data from the ONS showed that average earnings had risen by 2.1% in the year to November.
The number of people claiming Jobseeker's Allowance in December fell by 4,100 to 1.46 million, the ONS said.
Male unemployment increased by 43,000 in the three months to the end of November to reach 1.48 million, while female unemployment rose by 6,000 to 1.02 million. There were 157,000 redundancies, up by 14,000.
Most analysts, as well as the government, expect the unemployment total to continue rising, in large part due to the spending cuts designed to cut the budget deficit.
"At the headline level, [the jobless data] is fairly predictable," said Ross Walker at RBS Financial Markets.
"There is no significant change going on but there is a sense that the labour market is not showing any surge in activity a year into recovery. The underlying picture is still fairly subdued."
The British Chamber of Commerce was equally downbeat.
"These figures are disappointing and once again slightly worse than expected," said the group's chief economist David Kern.
"For the second month in a row, unemployment is up, employment is down and the level of inactivity has seen a marked increase."
Mr Kern re-iterated his forecast that unemployment would rise by 100,000 to 2.6 million over the next year.
On Tuesday, the Institute of Public Policy Research warned that the UK faced a double-dip in employment, with the jobless level expected to rise during 2011.
The think tank said that the UK economy was not growing fast enough to bring down unemployment.
The latest ONS data showed that average earnings rose by 2.1% in three months to the end of November compared with a year earlier.
Average total pay rose by 1.9% to £449 a week in the private sector, while public sector pay rose by 2.4% to £469 a week.
The number of employees and self-employed people working part-time because they could not find a full-time job increased by 26,000 to reach 1.16 million, the highest figure since comparable records began in 1992.
The demographic hit hardest by the tough jobs market was 16-24 year olds.
"Britain is now perilously close to seeing one million young people struggling to find work," said Martina Milburn, chief executive of youth charity The Prince's Trust.
"At this time when there is huge pressure on the public purse, government, charities and employers must work together to help young people into jobs and save the state billions."