(Fixes apostrophe in headline)
JOHANNESBURG, Jan 30 (Reuters) - South Africa's largest labour union group, with more than a million and a half members, said on Wednesday it would stage a nationwide strike on Feb. 13 over large-scale layoffs at ailing state-owned firms and at private companies.
The decision by the Congress of South African Trade Unions (Cosatu) poses a major threat to President Cyril Ramaphosa's plan to revive the economy by cutting the government's wage bill and reforming state firms that are drowning in debt and plagued by corruption.
The protests also come just months ahead of national elections, where Ramaphosa's governing African National Congress (ANC) is likely to struggle to maintain its large electoral majority amid stubbornly high unemployment and rising poverty.
Cosatu spokesman Sizwe Pamla said threats of deeper job cuts at state power firm Eskom and at public broadcaster SABC as well as other government plans to squeeze headcounts had prompted the decision for a nationwide strike by its 1.6 million members.
"We've deadlocked with the government and private sector on the issue of having a moratorium on retrenchments, and in that situation we had no option but to apply for this strike," said Pamla.
Eskom has announced plans to shed around 7,000 staff over the next five years. Loss-making state broadcaster SABC plans to lay off around 1,000 permanent employees.
Numerous mining firms also plan massive layoffs.
Impala Platinum plans to reduce its workforce by a third, Sibanye-Stillwater expects to cut 12,600 jobs over three years, and Gold Fields will shed more than 1,000 jobs. Lender Standard Bank aims to cut 526 information technology (IT) jobs.
Cosatu represents workers across mining, manufacturing, finance and the public sector, and through its alliance with the ANC has previously been able to influence government policy.
That influence has waned as divisions in the ruling party have widened. (Reporting by Mfuneko Toyana Editing by Gareth Jones)