031110 A new study has found that SA coal reserves have been significantly downsized since 2003.photo by Simphiwe Mbokazi 453

Johannesburg - The four unions representing coal workers in South Africa, the continent’s biggest producer of the fuel, rejected a pay offer by producers including Anglo American, Glencore and Exxaro Resources.

The companies proposed an increase of 4.6 percent, the Chamber of Mines, which represents them, said in an e-mail. The inflation rate was 4.6 percent in May.

The National Union of Mineworkers (NUM), Solidarity, the Association of Mineworkers and Construction Union and UASA labor groups rejected the offer, Franz Stehring, head of mining at UASA, said by phone Friday.

The NUM, the biggest labor group, wants a 15 percent raise for members, spokesman Livhuwani Mammburu said by phone.

The producers’ offer will “prolong the negotiations process,” Deon Reyneke, head of energy industry at Solidarity, said in an e-mailed statement.

South Africa’s coal-mining industry directly employs almost 90,000 people and paid about 19 billion rand ($1.5 billion) in wages in 2014, according to the chamber.

The talks are taking place as coal prices have dropped 31 percent since the start of 2014 amid a global supply glut that Morgan Stanley forecasts will grow due to lower demand from China.

Negotiations will resume on 21 July, the chamber said.