South Africa should adjust labour laws so union members have to vote before striking, Deputy President Cyril Ramaphosa said on Thursday, suggesting the government may push ahead with reforms to curb damaging industrial action.

A strike this year in the platinum sector, the longest and costliest in South Africa’s history, dragged the continent’s most advanced economy into contraction and led Standard & Poor’s to downgrade its sovereign credit rating.

Separately, the country’s biggest union, the National Union of Metalworkers of South Africa (Numsa), stopped work on July 2 to demand higher wages, halting output at several car factories.

The present system allows unions to declare a dispute with employers as soon as wage talks stall, and then call a strike without a ballot, giving employers just 48 hours’ notice.

Companies and politicians often argue that workers want to return to work but are intimidated into extending strikes by powerful union leaders.

“I would take a strike ballot as a normal type of process in the governance of strikes … I am hugely in support of that,” said Ramaphosa, a trade unionist-turned-billionaire seen as the most likely successor to President Jacob Zuma.

“In view of the length of strikes that we’ve seen … that is a matter that should be debated,” he told reporters in Cape Town, although added that any reforms should be handled “sensitively”.

Business leaders have long argued for the need to rein in the power of the unions, saying it is undermining the economy – a viewpoint denied by the labour movement.

“The central problem is not just the length of strikes. It is that the union leaders have too much power and no incentive to settle strikes,” the Financial Mail said in an editorial on Thursday.

“They should be bound to hold secret strike ballots. They should be forced to ensure that strikes are not supported by anarchic violence and intimidation,” it added.

Last year, the ruling African National Congress stalled on promises to amend labour laws to include strike ballots and picketing rules because of pressure from its labour federation partner, Cosatu, with whom it forms an official governing alliance.

Reforms will be hard to push through given that the right to strike is enshrined in South Africa’s post-apartheid constitution, allowing unions to argue that any alteration of strike laws is an infringement of their basic freedoms.

“We would be totally opposed to the government saying we must have a ballot,” Cosatu spokesman Patrick Craven said. “Each union has the democratic right to decide the best way to consult members.”