UPDATE 2-S.Africa's largest union NUMSA says to strike from July 1
* Strike set for July 1, union seeking 12 pct pay hike
* S.Africa still reeling from platinum strike (Recasts with strike threat, adds details, changes dateline from Cape Town)
By Zandi Shabalala
JOHANNESBURG, June 26 (Reuters) - Almost a quarter of a million South African workers in sectors from engineering to communications will strike indefinitely from July 1 in pursuit of a pay claim, the latest of a series of stoppages that have damaged Africa's most advanced economy.
South Africa's largest union NUMSA, which represents metal workers and other mostly skilled employees, said on Thursday the strike over wage demands was inevitable. It is seeking wage hikes of 12 percent against an inflation rate of 6.6 percent.
Employers are offering 8 percent, NUMSA said. It has said companies that would be impacted include Bell Equipment and industrial group Dorbyl.
South Africa is still reeling from a five-month strike in the platinum mining sector, which ended with a settlement this week. The government, keen to prevent more damage, said it would talk to all sides in a bid to prevent the NUMSA action.
"We are going to support all the affected parties to make sure this strike doesn't take place," Communications Minister Faith Muthambi told reporters during a briefing in parliament.
Yet the government's ability to influence NUMSA may be limited, as the union, once a political ally of the ruling African National Congress, refused to campaign for the party in elections this year because of disagreements over policy.
NUMSA, which has been having national talks with an employers' group called the Metal and Engineering Bargaining Council, claims to be South Africa's largest union with around 340,000 members, representing mostly black and urban workers.
NUMSA also said its 11,000 members at power utility Eskom would be willing to risk a wildcat strike, separate from its other national action, but gave no timeframe for any potential stoppage.
Workers at Eskom are generally not allowed to strike by law because they are considered to provide essential services. A downing of tools there by NUMSA members could hamper the utility's ability to keep the lights on, already a daily battle because of razor-thin margins between power supply and demand.
Labour unrest and frequent strike action have taken a toll on South Africa's reputation with investors and on its economy, which contracted in the first quarter of the year largely because of the platinum strike.
A four-week strike in 2013 by more than 30,000 NUMSA members at major auto makers cost the industry around $2 billion in lost output. (Additional reporting by Wendell Roelf in Cape Rown; Writing by Ed Stoddard; Editing by Joe Brock and David Holmes)