The National Union of Metal Workers (Numsa) has expressed concern at what it claims is an abuse of the police's airwing to intimidate striking Food and Allied Workers' Union (Fawu) members.

Numsa spokesperson Castro Ngobese said on Friday that this was similar to the restriction of airwing operations to a tiny minority under apartheid.

"We urge our allies in Popcru (the Police and Prisons Civil Rights Union) to engage their members not to be used to protect the interests of capital, and ABI (Amalgamated Beverages Industries) in particular," Ngobese said in a statement.

The police could not be reached for comment about the allegations.

Ngobese said Popcru members should understand that the ongoing strike action at ABI was a class struggle amid the exploitation and abuse of workers.

"It forms part of the many ongoing class struggles waged by workers and our communities for better delivery of services and decent work for all," he said.

He reiterated Numsa's call for a boycott of all ABI beverages until workers' demands for a "living wage" and the banning of labour brokers were met.

Hundreds of ABI employees affiliated to Fawu downed tools last week, demanding a 9.5 percent pay hike. The employer was offering 8.3 percent.

On Thursday, Fawu accused ABI management of provoking and intimidating employees after police helicopters were seen flying over the striking workers.

The union called on Police Minister Nathi Mthethwa and National Police Commissioner Bheki Cele to investigate the possible abuse or misuse of police resources.

"It cannot be right that police helicopters will be called, presumably by management, to fly above striking workers yet the dispatched police officials on the ground were not informed or did not see the need for such sheer show of power," Fawu general secretary Katishi Masemola said at the time.

ABI denied the claims of intimidation and provocation on Thursday, attributing the heavy police presence to workers' "escalating levels of violence" since the start of the strike.

The company accused striking workers of fire-bombing and stoning trucks, employee vehicles and delivery vehicles on Tuesday, and of intimidating non-striking workers.