Russian President Dmitry Medvedev is to make a landmark visit to Chernobyl later on Tuesday to take part in the memorial ceremonies at the site, joined by his Ukrainian counterpart Viktor Yanukovych.

In the early hours of April 26, 1986, workers at the Chernobyl atomic power station in the then Soviet republic were carrying out a test on reactor four when operating errors and design flaws sparked successive explosions.

Radioactive debris landed around the reactor, creating an apocalyptic scene in the surrounding area, while material also blew into the neighbouring Soviet republics of Belarus and Russia and further into western Europe.

Two workers were killed by the explosion and 28 other rescuers and staff died of radiation exposure in the next months. Tens of thousands needed to be evacuated and fears remain of the scale of damage to people's health.

AFP