Public security authorities in Central China's Hubei province have begun an investigation into the unnatural death of a detainee, who died by "drowning in a laundry basin with shallow water" as local county police and prosecutors claimed.

The case, which netizens dubbed as "bizarre", came amid concentrated efforts by the Ministry of Public Security to prevent unnatural deaths of suspects during law enforcement - a campaign following a series of deaths of detainees in the past year.

Xue Hongfu, 55, from Huangling village, was found dead by his roommate, surnamed Zhu, around 6:40 am last Wednesday in a basin in the yard of a detention center of Gong'an county, Jingzhou city of Hubei.

Xue was detained on March 27 for stealing a bicycle from a supermarket. He was serving 15 days in the detention center and fined 1,000 yuan ($147).

The basin, in which Xue was said to have drowned, is used for laundry, bathing and sometimes toilet-flushing. It measures 55 centimeters long, 47 cm wide and 46 cm deep, a local police spokesman surnamed Huang said.

An investigation conducted by the county police bureau and procuratorate showed Xue drowned and ruled out the possibility of police malpractice, a circular from the police bureau said.

Coroners also conducted an external examination of the body in the presence of Xue's family, who accepted the conclusion, Huang said.

The body was cremated around 6 pm the day after Xue's death, local media reported.

However, the explanation of Xue's death dissatisfied many netizens.

"Is that a basin or a swimming pool we're talking about?" a netizen named tianxiazhiboso said on the popular portal sohu.com.

The netizen is one among thousands who questioned the local police's "unusual explanation".

The Hubei provincial police department and Jingzhou city police bureau stepped in for inquiries about the case, Xinhua News Agency reported on Sunday.

However, neither police authority could be reached for comment on Sunday.

In recent years, cases of unnatural deaths in detention centers have sparked nationwide discussion about inmates' human rights and the proper management of detention houses.

Several inmates have died - according to police explanations - in unnatural ways such as bumping their heads into walls while playing hide and seek, hanging themselves with shoelaces or pant strings, tumbling to death while going to the toilet or drinking boiled water while being interrogated.

"Recently, unnatural deaths happened in succession in certain places. It has seriously harmed the public's confidence in law enforcement by police authorities," Meng Jianzhu, the Minister of Public Security, said late last month.

He urged local police to draw a lesson from it and try to prevent similar cases.

By Saturday, Northwest China's Gansu, Central China's Henan and North China's Hebei provinces reportedly issued policies that senior police officials should bear responsibility if their subordinates conduct any malpractice that results in the death of inmates.

For example, in Gansu province, police directors will be removed from their posts for unnatural deaths caused by malpractice such as police torture, misuse of guns or bullying inmates.