Hundreds of people have marched in Kenya's capital to protest against widespread corruption and deliver a petition to the office of President Uhuru Kenyatta.

Kenyatta is under increasing pressure as outrage grows over a number of corruption scandals revealed in recent weeks around the ministries of health, energy, agriculture, public service and youth.

Kenyatta, long criticized for not acting against corrupt officials, said Wednesday there "will be no mercy for the thieves."

This week 24 officials were charged with corruption-related offenses in a probe linked to the alleged diversion of nearly $80 million.

Kenya is considered among the world's most corrupt countries, ranked 143th out of 180 nations by Transparency International in its annual corruption index.