Mpumalanga premier Thabang Makwetla was at the Rob Ferreira Hospital in Nelspruit on Friday, visiting the survivors of the World Food Day bus crash.
Four people died in the accident, which occurred a few kilometres east of Graskop last Tuesday afternoon.
Three people died at the scene and one died in hospital on Thursday.
There were about 50 passengers in the bus. The injured were taken to nearby hospitals and several were transferred to Rob Ferreira.
The accident occurred when the bus failed to negotiate a corner in a sharp curve and plunged into a mountain gorge along the Kowyn Pass in Graskop.
Survivors told Sowetan, the police and Makwetla that the driver had been drunk and that they had warned him on several occasions that he was driving recklessly.
The bus passengers were returning from the World Food Day commemoration at Matibidi Soccer Stadium outside Graskop.
Makwetla's spokesman, Ntime Skhosana, said: "The premier gave the survivors flowers donated by the provincial department of agriculture and land administration.
"He wished them a speedy recovery and promised that their allegations about the driver being drunk would be thoroughly investigated."
Makwetla was accompanied by the MEC for agriculture and land administration, Madala Masuku, and by several mayors.
The victims at the Rob Ferreira hospital were Fekza Ngwenyama, a Mbombela councilor, Thalitha Mavuso, a local farmer, Zandile Bulunga, a poultry farmer in Mganduzeni, William Gulwako, an induna at Makoko village, Emma Mazibuko from Matafen, Ernest Thela from Sudwala and Solomon Radingoane from KaNyamazane.
Captain Tintswalo Ximusa, commissioner of the Graskop police, confirmed that the survivors had told the police that the driver of their bus had been drunk. He said the police had taken blood from the driver and that it was being analysed.
"We have sent the driver's blood samples to a laboratory to check the amount of alcohol that might have been in it.
"If it is established that it was above the legal limit the driver will definitely face the music," Ximusa said on Sunday.
Those who died in the accident were Nelly Ntombi Phiri, 49, of Matafen Farm, Jikijela Frans Molome, 58, of Malikutu Trust, Belile Cecilia Mkhabela, 44, of Matafen farm and Aniya Dludlu of KaBokweni Township.