Twenty-four tourists from south China's Guangdong province were injured in a bus accident in Taiwan on Friday, sources with a travel service in Guangzhou confirmed.

The victims were visiting Taiwan with a tour group of 30 people, said a public relations manager with GZL International Travel Service Ltd., which arranged the package tour.

The manager, who spoke on condition of anonymity, said the accident happened in a tunnel in the city of Chiayi Friday afternoon.

He said most victims suffered slight injuries. As of 9 p.m., 16 tourists were still under observation at a local hospital and the other eight had returned to their hotels.

Taiwan's tourism bureau said earlier that one tourist was seriously injured, while the others suffered skin abrasions.

The travel service in Guangzhou has promised to pay all of the victims' medical bills and ensure their rights and interests are protected.

The cause of the accident is not yet known.