The jobless total jumped by 7,000 to 2.52 million, ending a run of reductions, with all the increase caused by more 18 to 24-year-olds becoming unemployed.
The total is still 152,000 lower than a year ago, while the number of people claiming jobseeker's allowance fell in February by 1,500 to 1.54 million, the fourth consecutive monthly reduction.
There were 993,000 jobless 16 to 24-year-olds in the latest quarter to January, up by 48,000 from the three months to October, but the rise among 18 to 24-year-olds was 53,000.
The number of unemployed women increased by 5,000, the latest data from the Office for National Statistics showed.
Other figures revealed that public sector employment fell for the 13th consecutive quarter, by 20,000 to 5.7 million, the lowest for over a decade.
Local government employment fell by 32,000 and civil service jobs by 4,000, but the figure increased by 11,000 in central government.
Employment in private companies increased by 151,000 to 24 million.
The number of people out of work for between six and 12 months increased by 5,000 to 447,000, but fell by 16,000 for those unemployed for over a year to 887,000.
There were 29.7 million people in work, up by 590,000 on a year ago.
There were 8.9 million people classed as economically inactive, including those looking after a relative or who had given up looking for a job, a fall of 118,000.
Total pay rose by 1.2% in the year to January, down by 0.1% on the previous month and less than half the rate of inflation.
The unemployment rate remained at 7.8%, compared with 8.3% a year ago.
Regional unemployment between November and January (tabulate under region, total unemployed, change on quarter and unemployment rate)
North East 127,000 plus 3,000 9.8%
North West 301,000 plus 3,000 8.6%
Yorkshire and the Humber 246,000 plus 3,000 9.0%
East Midlands 178,000 minus 7,000 7.7%
West Midlands 241,000 plus 4,000 8.7%
East of England 207,000 minus 9,000 6.6%
London 365,000 minus 17,000 8.5%
South East 299,000 plus 16,000 6.6%
South West 156,000 plus 1,000 5.8%
Wales 125,000 plus 7,000 8.4%
Scotland 200,000 minus 4,000 7.4%
Northern Ireland 73,000 plus 5,000 8.5%