A mob in Kenya has killed a self-confessed serial killer, Mastsen Wanjala, who escaped from custody two days ago, police say.

The 20-year-old man was traced by villagers to a house in Bungoma town and beaten to death, they say.

Authorities had launched a massive manhunt for the fugitive who admitted to killing more than 10 young boys during a five-year period.

He also confessed to drugging them and in some cases drinking their blood.

He reportedly returned to the home of his parents, who have disowned him and was subsequently strangled by neighbours who found out he was there, an eyewitness told Kenya's Standard newspaper.

He tried to stave off suspicious locals by moving to a nearby house, Bungoma's police commander told the paper.

It is thought his family identified the body, although a police spokesperson said they are still doing "basic verification" to make sure the deceased is indeed Wanjala, according to Reuters news agency.

"We are not sure how he managed to travel all the way from Nairobi to his rural home," Musyoki Mutungi said.

"It is the curious villagers who first identified him and went ahead to kill him even before the police could be informed."