Kenyan President William Ruto has appointed a commission of inquiry into the deaths of more than 100 people believed to have been members of a cult whose leader ordered them to starve themselves to death, Ruto's spokesperson said.

Kenyan authorities say the dead were members of the Good News International Church led by Paul Mackenzie, who they say predicted the world would end on April 15 and instructed his followers to kill themselves to be the first to go to heaven.

The death toll stands at 111 but could rise further, in one of the worst cult-related disasters in recent history.

Some Kenyan lawmakers have criticised the security services for missing opportunities to prevent the mass deaths in the Shakahola forest after it emerged that Mackenzie had been arrested earlier this year on suspicion of the murder of two children by starvation and suffocation, then released on bail.

Mackenzie, who is in police custody, has not commented publicly on the accusations against him nor has he been required to enter a plea to any criminal charge. Two lawyers acting for him have declined to comment to Reuters.

Mackenzie and 17 others accused with him were appearing in court on Friday in the coastal city of Mombasa.

Presidential spokesperson Hussein Mohamed, in announcing the commission, said Ruto had also appointed a task force to review regulations governing religious organisations.

Among other things the inquiry will probe whether administrative or intelligence lapses contributed to the deaths. It will be chaired by Court of Appeal judge Jessie Lesiit, with psychiatrist Frank Njenga and bishop Catherine Mutua among the commissioners.