A bomb exploded in a hotel casino moments after security officers discovered it and evacuated the building, authorities said Saturday.

Police said the bomb caused no damage because a special blanket was thrown on it just before the blast. There were no injuries.The incident occurred Friday night at the Morula Sun, a resort hotel near Pretoria in the black homeland of Bophuthatswana. Gambling is illegal in South Africa, except in the homelands.

No one claimed responsibility for setting the bomb.

Police have blamed a recent series of explosions on the African National Congress, the outlawed guerrilla movement which since 1961 has waged a violent campaign aimed at toppling South Africa's white-led government.