JOHANNESBURG (Reuters) - Some 50,000 workers could go on strike at South Africa's port, rail and pipeline operations after wage talks with logistics group Transnet failed, a transport union said on Tuesday.

A strike at monopoly Transnet could cripple transport of coal and iron ore exports, distribution of fuel and shipping in Africa's biggest economy.

The South African Transport and Allied Workers Union (Satawu) said Transnet had offered to raise wages by 8 percent, while the union demands increases of 15 percent. The country's inflation rate stands at 5.7 percent.

The union said it will present Transnet's final offer to its members on April 22, when it will decide on whether to strike.

"Conciliation in a wage dispute between the two recognized unions and Transnet came to an end late last night, making way for the possibility of strike action across South Africa's port, rail and pipeline systems," Satawu said in a statement.

Transnet's staff are represented by Satawu and the United Transport and Allied Trade Union (Utatu).