Up until now public servants have missed out on contributions when they volunteer.
International development secretary Douglas Alexander said the change would encourage more public sector workers to volunteer.
A new£13m fund, supported by Department of Health, Department for International Development and Department for Children Schools and Families, is expected to
Cover pension contributions for approximately double the present number of volunteers
Will be available to volunteers leaving the UK between April 2008 and March 2011 for periods of volunteering of between 7-24 months
They will receive pension benefits, covering the absence based on their departing salary, when they return to the UK and continue in public service employment
No cost will fall to the employer or individual and the scheme is open to any member of a UK public sector pension scheme
Mr Alexander said: "Volunteering plays a valuable role in our society, not just in helping to reduce global poverty, but in the wealth of experience volunteers will bring back to the UK and into public service."
International development charity VSO chief executive Mark Goldring said: “This is a strong and welcome endorsement by the government of international volunteering. It recognises the critical contribution that public sector professionals can make to the fight against poverty through sharing their professional skills. It also acknowledges the huge benefits they then bring back to public service in the UK when they return with refined skills and a strong sense of personal and professional growth."
The announcement forms part of the government’s response to Lord Crisp’s report Global Health Partnerships , that made a number of recommendations last year to boost links between the UK and developing countries.
Education secretary Ed Balls said: "Teachers who volunteer bring back vital skills which feed back into UK education. They get management and leadership opportunities overseas that allow them to re-enter UK education with renewed focus or at a higher level.
"Ensuring that pension contributions are paid, at no cost to the school, local authority or individual teacher, will encourage more sabbaticals and career development breaks."