The labour market has improved in recent months across several key indicators -rising full-time employment, falling male and female unemployment, and faster wage growth - and the TUC will looking for further progress on all of these measures tomorrow.
But the TUC claims while unemployment has fallen by 51,000 over the last three months, the number of people out of work for at least a year has continued to rise amongst all age groups. Nearly half (44.5%) of unemployed workers aged over 50 have now been out of work for a year or more.
The TUC is concerned long-term unemployment amongst older workers can in some cases force them into premature retirement and poverty.
The number of 18-24 year olds out of work for at least six months has increased particularly quickly, rising by over a third in the last 12 months to reach 403,000.
The body said long spells out of work can permanently damage young people's career prospects and future earnings and the government should make tackling long-term youth unemployment its top priority, says the TUC.
The TUC has called for a guarantee of training or work paying at least the minimum wage for any young person out of work for at least six months, as well as a new youth credit to replace the scrapped Educational Maintenance Allowance, which will give young people more financial support to access training and skills.
It is concerned that too many of the work placements in the government's current employment schemes have no training, offer little chance of a sustainable job afterwards and risk squeezing out genuine job creation ahead of unpaid work experience.
TUC general secretary Brendan Barber said: "Falling unemployment has been the one bright spark in an otherwise gloomy economic climate so we'll be looking for more good news tomorrow.
"But even as unemployment falls, a growing number of people are being left behind and risk permanent career damage from long periods out of work.
"With around one in five young people neither in work or training, it's absolutely vital that the government puts in place adequate support to prevent an epidemic of long-term unemployment.
"Failing to invest in young people today not only carries a terrible personal cost for the individuals and their families struggling for work, but also carries long-term economic costs and increases the risk of social upheaval that no-one wants to see."