UPDATE 2-Unions threaten to ground South Africa's aviation industry

(Adds details, SAA response)

JOHANNESBURG, Nov 17 (Reuters) - Striking unions threatened to shut down South Africa's entire aviation industry on Sunday by extending industrial action beyond state-run South African Airways.

SAA has cancelled hundreds of flights since the strike began on Friday, saying the stoppage is costing 50 million rand ($3.36 million) per day and jeopardising talks with lenders around much-needed funding, threatening its survival.

The carrier and unions representing over half of its workforce held negotiations on Saturday that ended without an agreement. By Sunday, both sides were trading threats.

Phakamile Hlubi-Majola, spokeswoman for the National Union of Metalworkers of South Africa (NUMSA) which called the strike alongside the South African Cabin Crew Association, told journalists it was now consulting with its members at other organisations in the industry on a secondary strike.

"This secondary strike will have the impact of shutting down the entire aviation sector," she said. Consultations were underway with workers at SAA subsidiaries like Mango Airlines, other airlines like Comair and organisations like the Civil Aviation Authority and Airports Company South Africa.

She also said NUMSA had filed an application with the High Court to have the board of SAA Technical, a unit of SAA that provides aircraft maintenance, declared delinquent, and said flights SAA has restarted were unsafe.

Some of SAA's international flights have resumed though local and regional flights remain grounded.

SAA's acting CEO Zuks Ramasia called on the unions to retract statements made with regards to SAA's safety, saying that otherwise the airline would consider taking legal action.

Ramasia told a media briefing a secondary strike would hurt South Africa's competitiveness. "The intent of a secondary strike is to cause disruption, bring all airports to a halt and create huge damage to South African economy," she said.

The unions' plan could compound disruption by hitting airlines SAA has relied on to make alternative arrangements for its customers.

Their demands include an 8% wage increase and for outsourced services to be bought back in-house, and they also object to SAA's plans to axe more than 900 jobs. They say workers are tired of taking the hit for years of management failures.

SAA, which has not made a profit since 2011 and is reliant on government bailouts to survive, says it needs to cut costs. President Cyril Ramaphosa has staked his reputation on turning around a number of ailing state-run firms like SAA that the government has been forced to prop up.

Ramasia said that SAA had been tasked by dispute resolution body the Commission for Conciliation, Mediation and Arbitration, which mediated Saturday's talks, to consider options on the way forward with the unions.

"We are considering the options that were provided to us," she said, adding SAA will then revert back to the CCMA, whose commissioners will reconvene talks between the parties. (Reporting by Emma Rumney, editing by Louise Heavens and Philippa Fletcher)