Swiss newspaper 24 heures reported that federal energy councillor Simonetta Sommaruga wrote to International Atomic Energy Agency chief Rafael Grossi demanding the reduction of deputy director general Mikhail Chudakov's responsibilities.

Chudakov had long held a board position at a subsidiary of Rosatom, a public firm involved in the Russian army's occupation of Ukraine's largest nuclear power plant, Zaporizhzhia, the newspaper added.

Sommaruga asked for the Russian to be recused from matters relating to Russia and Ukraine and no longer receive confidential information, according to 24 heures.

Switzerland's federal energy office confirmed that Sommaruga wrote to Grossi on April 1 with those demands.

"For Switzerland, the independence and credibility of the IAEA as well as confidence in its activities are important," a ministry spokeswoman told AFP.

Rosatom is providing civil servants who are collaborating with Russian President Vladimir Putin's troops, and Chudakov's past played a part in Sommaruga's action, 24 heures reported.

Switzerland would have an interest in seeing security information being exchanged between Ukraine's nuclear authority, the Ukrainian government and the IAEA "on the basis of confidence and without any possibility of political influence", Sommaruga added in her letter.

Greenpeace, the environmental campaign group, had demanded the complete exclusion of Chudakov, who has served as head of the IAEA's nuclear energy department since 2015.

IAEA employees are instructed not to obey the orders of national governments or external authorities in their mission to ensure the safety of nuclear sites.

The IAEA in March adopted a resolution calling on Russia to immediately cease its actions against Ukrainian nuclear sites.

The IAEA did not immediately respond to an AFP request to comment, but 24 heures reported that the agency saw no reason to agree to Switzerland's demands.