The jobless rate in Greece reached a record high of 28% in November, according to newly released government figures.
The rate increased from 27.7% in the previous month. For those under the age of 25, unemployment hit 61.4%.
Harsh austerity measures have led the Greek economy to shrink by a quarter in four years.
However, other economic indicators have suggested that there are signs of recovery.
The BBC's Mark Lowen in Athens says the bleak unemployment numbers are in contrast to a message that the government has been trying to push: that Greece has turned a corner, with six years of recession due to end this year and light on the horizon.
He says the contrast with pre-crisis Greece is stark. Before the country received its first 110bn-euro ($150bn; £90bn) bailout in May 2010, the jobless rate was under 12% here.
Slight growth is expected this year and the deficit now wiped out, apart from interest payments on the bailout.
But our correspondent says that the government fears it will take a big hit in local and European elections in May.
Greek unemployment is more than twice the average rate in the eurozone.
The number of people out of work in the single currency bloc in December was 19 million, with the jobless rate at 12%, according to official EU figures.
Other economic figures such as retail sales, manufacturing activity and construction, have pointed to signs that Greece's recession has bottomed out.
However, Greece's unemployment rate is expected to rise further in the first three months of 2014 as firms continue to restructure and cut jobs.
"As expected, the labour market showed a lagging reaction to other positive signs in the economy, said economist Nikos Magginas at National Bank in Athens.
"The increase in unemployment is also due to a loss of support from tourism which was seen in the previous months."
With 1.38 million people officially jobless, turning around the country's economy will take time, even if the recovery does start this year as Athens hopes.
Before the crash when Greece was growing at up to 5% annually, about 50,000 jobs a year were added to the economy.
At these rates it could take more than 20 years to reduce the jobless totals - without measures to encourage domestic and foreign investment.