Shell has declared force majeure on fuel deliveries in South Africa's economic hub of Gauteng province, which includes Johannesburg and Pretoria, due to a two-week strike by more than 20,000 truck drivers, the company said on Friday.

"There is fuel available across the country so the issue is not fuel supply but the challenge is delivering it safely to our retail sites," the company said in an emailed response to questions.

Force majeure refers to a measure that covers the company and its customers should delivery of fuel not occur due to circumstances beyond their control.

(Reporting by Agnieszka Flak; Editing by Ed Cropley)