Premier Li Keqiang has ordered the full implementation of the country's temporary relief system and stronger government oversight of "left-behind" children in the wake of a case in which four siblings committed suicide by drinking insecticide in Bijie, Guizhou province.

Li said central government departments should increase the supervision of work at local levels and enhance the implementation of the temporary relief system, according to a statement released on the central government's website on Friday.

The four siblings were left behind in their home alone after the father, Zhang Fangqi, left for Guangdong province in March to work. The mother, Ren Xifen, left the family in March last year after a fight with her husband that left her hospitalized.

Qixingguan district government said on Friday that police have confirmed the children, between the ages of 5 and 13, died after ingesting a widely used insecticide on Tuesday night.

Bijie authorities said they have decided to suspend three government officials, including the deputy head of the Qixingguan district government and the district's education bureau chief, in the wake of the incident. The city and district have also set up a special investigative team.

The Ministry of Civil Affairs said on Friday it will review its social welfare network and offer psychological help to the needy.

The Guizhou provincial government started to carry out thorough checks on "left-behind" children across the province on Friday and said it will establish an archive system to keep track of all children without parental care.

Authorities have contacted the children's mother and she had returned. The Paper, a news website in Shanghai, reported that the father has been informed and will head back home on Saturday.

The four siblings had been skipping school since late April and rarely socialized with neighbors or other children, according to neighbors and relatives.

An aunt, Tan Ling, said the eldest child, Zhang Qigang, cooked for his sisters and also took care of the two pigs in the family's livestock pen.

He had been subjected to physical abuse by both his father and mother in the past. In one instance, his right arm was fractured by his father during a beating. In another, his mother forced him to stand naked in the sun for two hours.

The four children burned their textbooks after eating their last meal and ingesting the insecticide. Zhang Qigang jumped out of the window of their home and was found by neighbors, police said.

China Central Television reported that he left a letter saying the suicides had been planned for a long time.

The father and mother had been unable to assume their guardianship roles, said Qi Lianfeng, a lawyer specializing in family law at the Minghang Law Firm in Beijing.

"There is no evidence suggesting that the history of family violence has been a direct cause of the children's suicide. The parents will probably evade punishment," he said.

However, as the parents were unable to assume their guardianship roles, the local authorities should have filed legal action to take up guardianship, according to Chinese laws.

Xinhua contributed to this story.

xuwei@chinadaily.com.cn