South Africa's Kumba Iron Ore's production and exports will be hampered by a strike at state-owned logistics company Transnet, the miner said on Monday.

Transnet, which operates South Africa's freight rail network and all of the country's ports, declared force majeure at its ports on Thursday after some workers began a strike over wages.

"As a result of the disruption to Transnet’s rail and port services, the estimated impact on production is approximately 50,000 tonnes per day for the first seven days and thereafter approximately 90,000 tonnes per day. Export sales will be impacted by approximately 120,000 tonnes per day," Kumba said in a statement.

Kumba, which exports the bulk of its iron ore to China, Europe, Japan and South Korea, expects to produce and export between 38 million and 40 million tonnes of the mineral this year.

The company's production and exports were 40.9 million tonnes and 40.2 million tonnes respectively in 2021.

The United National Transport Union (UNTU) and the South African Transport and Allied Workers' Union (SATAWU), which together represent most Transnet workers, last week turned down Transnet's offer of a 3% to 4% wage rise, saying it was below South Africa's annual inflation rate, which was 7.6% in August.

(Reporting by Nelson Banya Editing by David Goodman )