Attacks against Jobcentre staff have risen by 62% since jobs were cut in the department 18 months ago, a union says.
About 11,000 civil service posts have been cut so far
Some centres were fast becoming like the "Wild West" because of the "alarming" rise in violence, the Public and Commercial Services Union said.
An internal document showed incidents included workers being punched, kicked and threatened with an axe.
A government spokesman said the number had risen because staff were now being encouraged to report such incidents.
But the Public and Commercial Services Union blamed job losses for the rise in assaults.
There were 329 physical assaults in Jobcentres in England, Wales and Scotland last year, compared with 203 in 2002, the union said.
Around 11,000 government posts have been axed at the Department of Work and Pensions and thousands more will go over the next few years in an overhaul of the civil service.
East of England - A man stabbed himself in the abdomen and threatened to kill himself
A young boy kicked a female worker in the stomach
A man threatened to use a knife against staff
London - A member of the public tried to assault a worker with a pair of scissors
A female worker had her arm held and twisted and needed hospital treatment
A worker was pushed to the floor and punched and kicked
West Midlands - A member of the public threatened to shoot a receptionist
Scotland - A man smashed the windows of 25 staff cars
South East - A man caused £1,400-worth of damage after smashing equipment.
Mark Serwotka, the Public and Commercial Services Union's general secretary, said: "This report lays bare the increasingly violent environment staff are having to work in and it is no surprise that there has been an increase in serious incidents as the axe falls on jobs.
"Violence against dedicated staff is unacceptable.
"Due to job cuts, some Jobcentres are now more like the Wild West as some of the most disadvantaged in society take their frustrations out on staff because they can't access the services they rely on.
"Staff suffering from assaults are low paid, with many facing losing their jobs, and it is deeply disturbing that they are increasingly expected to put up with physical violence.
"The government needs to seriously consider the impact that cuts and office closures are having on some of the most socially excluded in society.
"The fear is that if there isn't a rethink the number of serious incidents will continue to rise."
The Department of Work and Pensions said Jobcentres were equipped with CCTV cameras and panic alarms and had security guards on duty.
A survey last year found that staff generally felt safe in the new, open-plan offices, which they felt had a positive effect on the behaviour of customers, said a spokesman.
Staff were being encouraged to report all incidents, however minor, so that appropriate action could be taken against anyone who attacked them.
The department agreed there had been an increase in the statistics, but the spokesman suggested this reflected the increased awareness of reporting incidents.