Thousands of South Africa's national airline workers will stage an indefinite strike on Friday over planned job cuts and wages, unions said, days after the troubled carrier announced it would lay off hundreds of employees.

More than 3,000 workers including cabin crew, check-in, ticket sales and technical staff, as well as ground staff are expected to down tools in an opened-ended strike starting Friday, their unions said.

"We are embarking on the mother of all strikes," Zazi Nsibanyoni-Mugambi, president of the South African Cabin Crew Association (SACCA) told a news conference in Johannesburg on Wednesday, adding that unions had reached a "deadlock" with South African Airways (SAA) over wage demands.

"We are grounding the airline on Friday," said Irvin Jim, general secretary of the National Union of Metalworkers of South Africa (NUMSA).

The state-owned airline on Monday announced a restructuring process that could affect 944 employees and "lead to job losses".

South African Airways (SAA) is deep in debt and has been struggling despite several government bailouts.

The workers who are also demanding an eight percent across-the-board wage hike want "job security for at least three years".

The airline employs 5,146 workers.

The unions blame the SAA board and executive management for the crisis roiling the airline.

"Through their actions, they have deliberately destroyed what used to be one of the worlds' best airlines, because of maladministration, rampant looting and corruption," the unions said in the statement read by Nsibanyoni-Mugambi.

Finance Minister Tito Mboweni announced in February that the government would reimburse the company's 9.2-billion rand debt (around $620 million) over the next three years.

The airline has not posted an annual profit since 2011.

South Africa is struggling to get its state-owned companies back on track after nine years of corruption and mismanagement under former president Jacob Zuma.

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