Staff cuts and the casualisation of Centrelink's workforce is dragging out waiting times, increasing customer complaints and causing significant public anger, a union report finds.

The Community and Public Sector Union published a report on the state of Centrelink call centre services, which found customers were routinely waiting between 60 to 90 minutes to have their call answered.

It found understaffing and a ''deteriorating workforce'' were having a dramatic impact on experiences of customers. The union found staffing levels had remained constant since 2002, despite the number of calls increasing by 63 per cent.

It now takes staff 12 minutes on average to answer a call, up from 1.8 minutes in mid-2002.

CPSU national secretary Nadine Flood said the federal government's efficiency dividend and a shift to temporary, contract-based workers were hurting the agency.

''It is not acceptable that thousands of vulnerable Australians who rely on Centrelink payments to survive are being forced to use an overstretched and under-funded service,'' she said.

''There is an urgent need to lift permanent staffing levels in Centrelink call centres to address its staffing crisis.''

Human Services Minister Kim Carr said he would meet with the union to discuss issues at Centrelink. ''We acknowledge that there has been an increase in waiting times due to unprecedented levels of demand, and we are committed to working with the unions to improve services for the public,'' he said.

The government provided supplementary funding over four years to maintain 600 positions in the call centre.