JOHANNESBURG — Officials blame thieves for power problems at South Africa’s main World Cup stadium, but the stadium manager promised Friday the lights will be on in time for a U2 concert.

The theft of power cables in the area around Johannesburg’s FNB Stadium led to fluctuations in supplies that can damage generators and other equipment, stadium manager Jacques Grobbelaar said Friday. City Power spokesman Sol Masolo said his utility had asked police to investigate a case of cable theft in the matter.

Cable theft, widespread in South Africa and elsewhere, is likely to increase with recent global copper price rises.

A national soccer league game scheduled for Saturday at the stadium had to be canceled to allow for repairs before the U2 concert, Grobbelaar said.

Grobbelaar said U2 is expected to draw 98,000 fans, making the Feb. 13 concert a bigger event than the World Cup final, when the stadium hosted about 94,000 people.