South African unions on Sunday called on all aviation workers to join striking South African Airways (SAA) staff after the cash-strapped airline failed to meet their demands.

The country's embattled flag carrier has been losing 52 million rand ($3.5 million) per day since more than 3,000 workers started an open-ended strike on Friday -- forcing the airline to cancel hundreds of flights.

Talks with the two unions representing the striking workers ended without resolution on Saturday, prompting threats of further action.

"In response to this deliberate provocation by the SAA board and its executive management, (the) NUMSA (metalworkers' union) is in the process of consulting workers for a secondary strike in aviation," NUMSA spokeswoman Phakamile Hlubi-Majola told reporters in front of the SAA headquarters in Johannesburg.

NUMSA and the South African Cabin Crew Association (SACCA) first threatened to strike after SAA announced this week that almost 1,000 employees could lose their jobs as part of a restructuring process.

Initial talks with management deadlocked after they failed to agree on wage hikes, prompting the unions to press on with their threats.

SAA is offering a 5.9 percent pay rise, while unions are demanding an eight percent across-the-board hike and a three-year guarantee of job security.

They are also asking the airline to in-source more jobs.

"We are fighting against retrenchment, corruption and privatisation," Hlubi-Majola, told journalists.

She said discussions with SAA subsidiaries, South Africa's airport management company and airline service providers were underway.

"This secondary strike will have the impact of shutting down the entire aviation sector," said NUMSA and SACCA in a joint statement.

SAA did not immediately respond to AFP's requests for comment.

More than 300 flights have been grounded as a result of the open-ended strike.

Some international flights are scheduled to resume on Sunday evening, while regional and domestic flights have been cancelled until Monday included.

"South African Airways advises customers that following the industrial strike action if you do not have a confirmed booking for your flight do not go to the airport," SAA tweeted on Sunday.

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.

SAA -- one of the biggest airlines in Africa -- is deep in debt and has not posted a profit since 2011, despite several government bailouts.

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

sch/har

South Africa Jacob zuma