Gauteng police have launched a manhunt for two "most wanted" serial rapists who have terrorised residents of Gauteng, Limpopo and KwaZulu-Natal.

The two men - Sipho Mbatha, 32 and Orence Makhubela, 37 - are wanted in relation to more than 20 cases, including rape and other serious offences.

Police spokesperson Colonel Lungelo Dlamini said Mbatha - who uses several surnames, including Ntombela and Mthethwa - was wanted for crimes that took place in areas of the Lawley informal settlement, in Johannesburg, and in parts of Soweto.

Mbatha is out on parole after being convicted for a rape in Paulpietersburg. He was sentenced to 15 years in prison.

"Mbatha is known for terrorising the residents of the Lawley informal settlement and Soweto. He would threaten to kill the victims if they report him to the police. A warrant of arrest has been issued for him for more than 10 cases of rape, kidnapping, pointing of a firearm, attempted murder and armed robbery," said Dlamini.

Makhubela is wanted in connection with 13 cases of rape in Diepsloot and Westonaria.

"He is suspected to be in the areas of Tzaneen in Limpopo, or Diepsloot. He had been attacking his victims in the early hours of the morning or late at night. He is also wanted for other serious crimes, including housebreaking, house robbery, kidnapping, theft and attempted rape. A warrant for his arrest has also been issued," he said.

"Members of the Gauteng Family Violence, Child Protection and Sexual Offences Unit are appealing to the members of the public to be on the lookout for, and assist in tracing, two most wanted suspects who have been involved in serial rape and other serious and violent crimes in Gauteng, Limpopo and Paulpietersburg in KwaZulu-Natal," he said.

Dlamini said Mbatha and Makhubela might be armed and were considered to be dangerous.

Members of the public were advised not to confront them, but rather to contact the nearest police station or the investigating officer.

Anyone who may know the whereabouts of the two suspects can contact Sergeant Jack Ngobeni at 079 890 7936 or Crime Stop at 08600 10111 at all hours.

Dlamini said that anyone with information that could lead to the arrest of the two men may be rewarded.