Three senior police officers were sacked on Sunday and four policemen were placed under investigation after a suspect was allegedly tortured to death in a detention house in Henan province on Feb 21.

Henan's provincial public security department said Zhang Guanjun, director of Lushan county's police bureau, was ordered to resign on Sunday for bearing responsibility for the case.

The bureau's deputy chief and another senior officer in charge of criminal investigations were removed from their posts, pending further punishments, the department said late on Sunday.

Four other policemen suspected of torture during interrogation were handed over to local prosecutors for investigation.

Wang Yahui, a theft suspect from a local village, died three days after he was detained by local police.

The incident gained wide public attention after Yao Jin, director of the political department of the country's police bureau, told a local news channel that Wang died "after drinking some sort of water during interrogation".

Wang's family strongly disagreed with the police version after they were allowed to see the body on Feb 22.

Wang's aunt, surnamed Wu, who accompanied Wang's mother to the hospital mortuary that day, said she was shocked to see cuts and bruises all over Wang's body.

Video footage shot by the family, which was also broadcast on Henan TV, showed Wang's nipples were seriously wounded. Bruises and injuries were also found on his arms, head and genitals.

The family said they suspect the bruises resulted from police torture and demanded an autopsy.

Even as China has striven to curb the practice of torture during interrogation by improving the judicial mechanism, detention deaths have been frequent in recent years.

Last month, three former policemen found guilty of torturing a high school student were sentenced to up to two and a half years in prison.

Autopsy results showed the student died of heart failure resulting from torture in March last year.

The Ministry of Public Security has said that preventing the unnatural deaths of inmates in detention houses is a key task for the police.