Police said today that a Russian investigative journalist who was detained this week for alleged drug offences had been taken to hospital, Russian news agencies reported.

Ivan Golunov, 36, was on his way to a meeting with a source on Thursday when he was taken into custody in central Moscow and illegal drugs were found in his rucksack, according to police and his employer, the online news portal Meduza.

A lawyer for Golunov, who is known for investigating alleged corruption among Moscow city officials, said he believed police had planted the drugs on his client to frame him and that Golunov had been physically beaten.

"The detainee ... complained of feeling unwell. An ambulance was called... The ambulance doctors decided that he should be taken to a hospital for examination," Interfax quoted a Moscow police press office as saying.

A Moscow court was due to decide on pre-trial restrictive measures today.

The editorial management of Meduza, which is based in Latvia, said in a statement that Golunov had received threats in recent months in connection with a story he was working on.