A coalition including the TUC, Demos, the Work Foundation and former Cabinet minister James Purnell warned of the danger of repeating the "mistakes" of the last two recessions, when unemployment was allowed to "spiral out of control".
The number of long-term unemployed continued to rise for 18 months after the 1990s recession ended, it was pointed out.
In a letter to Work and Pensions Secretary Yvette Cooper, the coalition warned that spells of long-term unemployment increased the likelihood of mental health problems, relationship breakdown and issues relating to alcohol, debt and homelessness.
To counter rising long-term unemployment, the coalition said the Government should introduce a universal job guarantee for anyone who has been on jobseekers' allowance for more than 12 months.
TUC general secretary Brendan Barber said: "While recent economic indicators offer reasons for cautious cheer, unemployment remains a huge concern.
"There must not be a repeat of the last two recessions, when millions of people were stuck in semi-permanent unemployment long after the economy had recovered.
"Long periods out of work can have a devastating impact on people's health and mass unemployment can crush communities. A universal job guarantee would help prevent this.
"A job paying decent wages for at least six months provides the kind of experience employers want and gives an unemployed person the best possible chance of getting back to work."
The move came ahead of new figures on Wednesday which are expected to show another increase in unemployment.