A judge in Slovakia has stepped down after being linked with a businessman accused of ordering the killing of an investigative journalist, officials said on Thursday.

Bratislava judge Miriam Repakova is among several members of the judiciary alleged to have exchanged text messages with murder suspect Marian Kocner. She is the first judge to be forced to step down.

The businessman is accused of ordering the February 2018 murder of Jan Kuciak, a reporter who had been investigating Kocner's business activities.

The killing triggered mass protests that forced Prime Minister Robert Fico to resign, and inspired anti-corruption activist Zuzana Caputova to successfully run for president.

It was revealed in March that he had a Malta connection as he used to be a director of a company registered in Malta.

Presidential spokesman Martin Strizenec said the judge had resigned on Wednesday but would continue to serve until the end of November.

Prosecutors have charged Kocner with ordering the assassination of Kuciak and are also investigating his role in several cases of suspected fraud.

Four other people were also charged, including one suspect who has cooperated with investigators in exchange for a plea bargain.

In September, justice ministry official Monika Jankovska resigned after the leak of thousands of text messages she had exchanged with Kocner.