Work and Income offices in Christchurch have reopened after police have charged a man who threatened to shoot staff at the Linwood Office.

The man was turned away from the building and threatened to return and open fire.

Six Ministry of Social Development offices across Canterbury closed as a precaution, they have now all reopened.

The 50-year-old man is due in court next week.

"Police would like to reassure members of the public that no firearm was sighted by the security staff and nor was one located during a search of a residential property," Detective Superintendent Peter Read says.

Newshub.