US ambassador to South Africa Patrick Gaspard has added his voice to a growing chorus of concern about the country’s volatile labour relations climate, saying it is having a “serious impact on foreign investment”.

Speaking in Pretoria at an event organised jointly by the University of South Africa and the Institute for Global Dialogue, Gaspard emphasised his own union record, having served as an official of the local union of the Service Employees International Union. Nevertheless, he warned that American companies were communicating their concern about recent strikes, which were often associated with violence and damage to property.

He said the disputes were making it difficult for these companies to convince their international boards to take on the risk of investing in South Africa. “And this will lead to fewer jobs in the long run, not more stability for a vulnerable workforce.”

His remarks came as the Association of Mineworkers and Construction Union (AMCU) indicated that it planned to continue to strike at the operations of platinum miners Anglo American Platinum, Impala Platinum and Lonmin – the world’s three largest producers of the precious metal. However, the union did indicate that it might be willing to be flexible on its demand for an entry-level monthly wage of R12 500, if the chief executives of the three companies were willing to become involved directly in the wage talks.

A day earlier, the CEs made a joint appeal for AMCU members to return to work and accept a three-year transition to their R12 500-a-month wage demand, which was not immediately affordable.

The ambassador’s remarks also followed President Jacob Zuma’s appeal in his State of the Nation address for mine owners and mineworkers to put the economy and job security first as they negotiated a resolution to their disputes. Deviating from his prepared address, Zuma said there was “no way we can have conflict that destroys the economy”, while stressing that the country needed “a mining sector that works”.

“It must not be easy for anybody to say: ‘Let’s strike’. Or for somebody to say: ‘I’m now reducing the workforce’. All of us must think together,” Zuma said during a joint sitting of both houses of Parliament, where union leaders were among invited guests.

The total employees complement of the three platinum mines had already fallen from 145 000 in December 2011 to fewer than 134 000 by December last year and there were warnings that prolonged strike action could result in further job losses and even mine closures.

Gaspard stressed that workers had a right to strike, adding: “I will favourably stack up my fierce advocacy for the collective voice of workers against anyone”. But he also argued that, while strike action was an important tool, it could not “be the first tool of the labour movement because of its profound impact, in both human and economic terms”.

He reflected on being an organiser of a transport-workers strike “that crippled a city, cost businesses billions of dollars and ultimately hurt the cheque books of the striking workers themselves”. By contrast, he had also participated in a number of other actions that had yielded results in the absence of actual strike activity.

“The current shape of the conflicts [in South Africa] can be a vicious cycle. Workers are exploited; they disrupt the enterprise, making the employers lose money; foreign investors go elsewhere; workers fall further into debt; and no one speaks for the scores of long-term unemployed who have never had the benefit of a union.”

Workers and business owners, he added, had a shared investment in a collective future and both sides needed to take a long-term view of how they both could prosper, rather than securing a demand or winning a concession.

“Everyone’s goal should be an economically strong and sustainable industry that employs the largest number of workers, with strong wages and benefits.”

Gaspard warned that investors had already taken note of the volatility, highlighting that, while Toyota and Mercedes-Benz had made recent investments, others were being turned off. Examples cited included Datsun’s recent decision to locate its factory in India rather than South Africa and BMW’s decision last year not to add an additional export platform to its existing domestic production.

South Africa, Gaspard stressed, has a strong framework for labour mediation.