UK unemployment rose by 118,000 in the three months to November to 2.685 million, official figures show.
The Office for National Statistics (ONS) said the unemployment rate also rose to 8.4% from 8.3%, the highest since January 1996.
The number of people claiming Jobseeker's Allowance in December rose by 1,200 to 1.6 million.
The number of young people looking for work rose to 1.043m, taking the rate for 16-24 year-olds to 22.3%.
The number of people in employment rose slightly in the three months to November by 18,000 to 29.119 million.
The figures support the picture of a flat UK economy, with other data released on Wednesday showing average weekly earnings, including bonuses, grew at just 1.9%.
There are few crumbs of comfort in the latest figures from the labour market. Once again the increase in the claimant count (covering those signing on for Jobseeker's Allowance) was only marginal - just 1,200 in December.
This suggests the narrower measure of the jobless total may be flattening out at 1.6 million. The number claiming JSA for less than 6 months fell by 16,500 in the month.
But the overall unemployment total rose again - the 118,000 increase over three months showing no sign of an easing of the upward trend.
A fall in the employment rate and an increase in the equivalent jobless rate underlines a gloomy picture.
The Employment Minister, Chris Grayling, said the figures were worrying.
"The overall level of unemployment is, and will remain, a major concern for the government,
"However, I should say that these figures are much more complex than the headlines first suggest. In reality, the number of people in employment has gone up; the level of people on Jobseeker's Allowance, when you take into account changes in our welfare system, has actually gone down slightly; the number of people on out of work benefits has come down over the last few months since the general election."
Labour's shadow work and pensions secretary, Liam Byrne, said: "Last month Chris Grayling told us how the labour market was stabilising, but today's figures now confirm we have an unemployment emergency."
In Scotland, the number of people out of work rose by 19,000 to 231,000 over the three months to November, giving a jobless rate of 8.6%.
In Wales, unemployment fell by 1,000 in the quarter to 130,000, giving a rate of 8.9%, while in Northern Ireland it fell by 7,000 to 59,000, giving a jobless rate of 6.8%.
Since the period covered by the latest ONS figures, there have been a number of job loss announcements from retailers and banks, and the government's public sector cuts programme is continuing.
Ross Walker, economist at RBS, said the numbers were unlikely to improve in the coming months: "Overall, there's a slightly softer feel to these figures. The labour market is struggling and forward-looking indicators such as vacancies and hiring intentions suggest it's going to be rocky in the first half of this year."
Paul Kenny, the general secretary of the GMB union, blamed the government for the increase, saying: "This rise in unemployment was made in Downing Street. The truth is that jobs are haemorrhaging in the public and private sectors and no one in the government seems to know what to do to stop this."
On Tuesday, figures showed that the rate of inflation fell from 4.8% to 4.2% in December, which was seen as increasing the chances of another cash injection from the Bank of England when its current quantitative easing programme ends.