BEIJING (REUTERS) - Two Chinese police officers acted improperly in the arrest and detention of a well-known environmentalist who died in police custody last month, state media reported on Thursday (June 30), a case that sparked a public outcry.

The officers had been detained and accused of dereliction of duty, as well as impeding the course of the investigation, the official Xinhua news agency reported online.

Lei Yang, who was accused of visiting a brothel, died of asphyxiation, Xinhua said, though the report did not elaborate on the exact circumstances of his death.

Lei died just hours after being taken into police custody according to local media reports.

Beijing police could not be immediately reached for comment.

The finding is a rare indictment of law enforcement officers in stability-obsessed China, where courts answer to the ruling Communist Party, which is also the top authority governing police.

Police brutality cases rarely become major news in the country, where there is little oversight over law enforcement. Hundreds of comments on Chinese social media expressed outrage after the case came to light, criticising a lack of transparency.

Lei, from the central province of Hunan but living in Beijing, was married and had a daughter who was born just weeks before police detained him, according to media reports.