Four former Russian policemen on trial for planting drugs on a prominent investigative journalist denied the charges against them on Thursday.

The arrest of reporter Ivan Golunov in June 2019 on trumped-up drug charges spurred a massive campaign calling for his release led by activists and Kremlin critics.

His supporters and employer -- the independent Russian-language media outlet Meduza -- said the narcotics had been planted on him as revenge for his work.

Golunov, 37, was released days later after un unprecedented campaign in support of him, and the five police officers who arrested him were dismissed and taken into custody in January.

One of the five men has confessed to planting drugs on the journalist and is under house arrest.

During a court hearing in the Moscow City Court on Thursday, former policeman Igor Lyakhovets, suspected of organising the fabrication of the evidence, refused to admit guilt, Russian news agencies reported.

His three subordinates also denied the charges.

The trial was adjourned until January 12 when Golunov is expected to be questioned, said the journalist's lawyer Sergei Badamshin.

-He's attending every hearing- Badamshin told AFP.

The investigative journalist's detention shone light on widespread corruption among Russia's police force, whose members are an essential pillar of President Vladimir Putin's 20-year rule.

Investigators have accused the men of falsifying the results of evidence-gathering operations and illegally buying, storing and transporting drugs.

Golunov is celebrated for detailed investigations into power structures in Russia including the shady funeral industry and corruption at Moscow city hall.

During his two decades in power, Putin has silenced most of his critics and a dwindling number of independent media outlets say they are coming under increasing state pressure.

The editor of an independent news website, Irina Slavina, died in Nizhny Novgorod in October after setting herself on fire following a police raid.