Over 30,000 workers began an indefinite strike Sunday after wage negotiations in South Africa's coal industry failed.

"We took the decision to strike because we reached a deadlock," National Union of Mineworkers (NUM) spokesman Livhuwani Mammburu told AFP.

"It will continue indefinitely until the two parties can come together and solve their differences."

The strike, which was scheduled to begin at 1600 GMT on Sunday, will hit mining houses Anglo American, Exxaro and the embattled Anglo-Swiss giant Glencore.

The latter firm has in the past few months cut hundreds of jobs in an attempt to reduce costs.

In August, it announced it was putting its Optimum Coal Mine, which supplies the state-owned power generator Eskom, into a form of bankruptcy protection as it seeks to restructure the company, citing "unsustainable financial hardship".

The NUM is demanding a 14 percent increase for its miners, artisans and officials, and a 13 to 14 percent increase -- or R1000 ($73) -- for the industry's lowest paid workers.

After over three months of negotiations, the industry bosses have come to the table with an offer of only about half the requested wage rises.

"Striking is the only way for the workers to express their dissatisfaction with these offers," said Mammburu.

According to the Chamber of Mines, South Africa's coal industry employs about 90,000 people.