Stones have been lobbed at Numsa’s head office in Newtown, Johannesburg, breaking six windows and damaging a sign, police said on Tuesday.
A man was seen throwing stones at the National Union of Metalworkers of SA (Numsa) building at 2am on Monday, said Warrant Officer Xoli Mbele.

“The security guards tried to chase him, but he got away,” he said, adding that a case of malicious damage to property was being investigated.

“[We] are shocked and devastated by this latest attack on our head office, which is a property built on workers meagre wages,” Numsa spokesman Castro Ngobese said in a statement condemning the attack.

He said that this was not the first case the union had reported to the police.

Last year, computers were stolen from the building on more than one occasion by “well-dressed young men”, and a Numsa-owned car was stolen outside the building.

Ngobese said it was sad that after 19 years of democracy the union was still having to deal with the issues of security it had on its property under apartheid.

The Congress of SA Trade Unions (Cosatu) also condemned the attack and called on unions to support Numsa.

“Remember that your offices could be next. An injury to one is an injury to all,” Cosatu spokesman Patrick Craven said in a statement.