African National Congress (ANC) presidential hopeful Mathews Phosa has condemned the bomb threat that targeted the attorneys' offices where he is a partner in Mbombela, Mpumalanga, only two days after launching his campaign in the province.

Phosa, who was not in the province at the time,  said he received a phone call on Friday morning about bomb threats made to the office.

"I wasn't there. I got a call from one of my young partners who asked if I heard about it. This is sickening," he said.

"It worries me that this happens two days after the launch of our campaign in the province. Why does it happen? It must be condemned," he said.

Phosa said he was concerned about the threat following a break-in at one of his campaign offices in August where a server with sensitive campaign intelligence was stolen.

Phosa, a former treasurer general of the ANC and premier of Mpumalanga, has been a vocal critic of President Jacob Zuma. He is also a hopeful for the ANC presidency ahead of the elective conference in December this year.

"This is the third incident. We've received similar threats. There has been a lot of violence in Mpumalanga and it worries me. What do they fear in the battle of ideas," he said.

"It challenges the myth that it is a united province," he said. Phosa called on the police to investigate the matter and find the perpetrators.

"The police must take it seriously and investigate it and get to the bottom of this. We can't have it happen in South Africa," he said.

Nelspruit police spokesperson Captain Dawie Pretorius confirmed the bomb threats and said police would release a statement later on Friday.