Threats and assaults on Work and Income staff in Canterbury doubled after the fatal shooting in Ashburton two years ago.
There were 432 security incidents reported in Canterbury offices in the year from July 2014 to June last year, up from 212 the year before.
At the Linwood office alone there were almost 100 security incidents, including 13 rated serious and 11 where police had to be involved.
Christchurch Work and Income offices have been closed or placed in lockdown at least four times since the Ashburton shooting, because of threats.
Ministry of Social Development Canterbury regional commissioner John Henderson said extra security guards had been put in place at all sites since the shooting.
"The Ministry has always taken threatening behaviour seriously and since the tragedy in Ashburton on 1 September 2014 we have implemented a zero tolerance policy towards such behaviour. Every threat is taken seriously."
He believed staff were reporting more incidents because of the policy, which could have contributed to the rise.
He said the ministry was developing new layouts for the offices which would "balance privacy, visibility, safety and service".
There were 97 security incidents in Linwood in the 2014-15 year, and another 62 in the nine months to March this year.
But Riccarton had the most police involvement, with police having to be brought in over one in five security incidents, compared with just one in ten at Linwood.
Police had to be brought in to deal with 90 incidents at different offices over the year.
Security incidents include anything from threats to physical attacks, and are rated minor, moderate, serious or critical.
Incidents are ranked critical if someone is seriously injured and needs hospitalisation, if someone is killed or if there is a bomb threat or arson.
Serious incidents range from physical harm that leaves someone needing medical treatment to things like stalking of staff.
Security incidents at Work and Income centres between July 2014 and June last year:
• Linwood: 97
• New Brighton: 59
• Sydenham: 44
• Rangiora: 38
• Papanui: 37
• Riccarton: 34
• Hornby: 30
• Shirley: 24
• Ashburton: 18
• Kaiapoi: 9
• Christchurch Metro: 3
• Akaroa: 0
• Outside offices: 33
Christchurch WINZ lockdowns
September, 2014: Christchurch Work and Income offices were put in lockdown after a threat was made against staff, just days after the Ashburton shooting.
October, 2015: A 33 year old man threatened staff at the Linwood Work and Income office with a gun and fired it into the air, but was not able to get inside the office. He was arrested by police as he tried to drive away from the office, and sentenced to two years eight months in prison.
February, 2016: Six Work and Income offices across the city were put in lockdown after a 50 year old man who was turned away from the Linwood office threatened to return with a gun and start shooting. He was later arrested.
May, 2016: Work and Income offices were closed after two people called and threatened staff at the Hornby, Linwood and Sydenham offices.