At least 26 people have been killed and many others injured in a head-on crash between a bus and a truck on the highway between Nairobi and Kenya's second city Mombasa.

A police spokesperson said the bus, heading to Mombasa, was overtaking several vehicles when it collided with an oil tanker in the Kibwezi area.

Most of those on the bus were families returning from Easter festivities and students preparing for the reopening of school after holidays.

Three children were among the dead. Another 19 people were injured.

Kenya has a poor road safety record, with up to 3,000 people killed each year according to police.

The World Health Organization puts the toll at 12,000.

In December at least 40 people were killed in a crash around 100km northwest of Nairobi, in which a tanker smashed into several other vehicles before exploding.