Numsa warned of a fake account on social networking site Twitter, which claimed to belong to its general secretary Irvin Jim.
"It is a fake account and has nothing to do with either comrade Irvin Jim or Numsa and therefore the views expressed in it do not come from comrade Jim or Numsa," National Union of Metalworkers of SA spokesman Castro Ngobese said in a statement.
"Comrade Irvin Jim shall take no responsibility for any postings made in his name on any other Twitter account other than the one he created with the handle @IrvinJimSA."
The fake Twitter account @IrvinJim_NUMSA had been removed.
Ngobese said Numsa had reported the account to Twitter and asked that it be shut down.
Government on Monday also warned the public saying those who followed developments in government via social media should do so through authentic accounts linked to departments' websites.
"Government communications is aware that a number of fake accounts have emerged following President Jacob Zuma's announcement of the new national executive," government spokeswoman Phumla Williams said.
"Government wishes to clarify that people wanting to follow developments around the new Cabinet on social media are advised to access Twitter and Facebook accounts via the respective departmental websites."
This was after the National Treasury warned of a fake Twitter account claiming to be that of newly appointed Finance Minister Nhlanhla Nene.
Just R20 for the first month. Support independent journalism by subscribing to our digital news package. 
