When photos of two orphaned children bound in chains at a government-run welfare institute in Wenzhou's Cangnan county was published in the local paper, it rocked the whole country.

Experts said a lack of professional nursing staff was the main reason the children were chained and said such cases occurred at welfare institutes across China.

The photos depicted 2-year old Guo Qun tethered to the back of an old wooden chair by a strip of cloth around his neck. Next to him 8-year old Guo Cheng's right foot was tied to the same chair by an iron chain.

The photos were taken by a volunteer during a visit to the welfare house in June.

In comments that have shocked the public, authorities said staff of Cangnan County Social Welfare Institute tied up the boys due to safety concerns and claimed they were not being punished.

"Although the president of the welfare house was suspended, the staff were not as they didn't do it with intent," said Wu Jiaxing from Cangnan's civil affairs bureau. "Children (of the welfare house) are only restrained when they have a twitch or a propensity to violence — they're free for the rest of time."

According to Wu, both the boys were born with defects and that is why they ended up in the welfare institute.

"Guo Qun is suffering from congenital deafmutism and he has epilepsy, that's why staff has to fix him (with a strip of cloth) when he relieves himself — he's incontinent," said Wu. "Guo Cheng has schizophrenia and he's capable of violence."

However, the photos of the boys in chains were taken during mealtime and both boys were locked up while eating. Zhejiang province's local newspaper Modern Gold News quoted an anonymous staff who admitting they tied up the children. The anonymous staff member said the last time she saw the children restrained was on June 29, it was raining outside but Guo Qun and Guo Cheng kept running out to play— they wetted their clothing three times prompting the staff to lock them up to stop them going outside.

Cangnan County Social Welfare Institute houses 21 orphans, 19 of them were born with defects. The average age is 9-years old.

"They (the staff) just lack knowledge on child caring," said Wu. He said there are only four carers taking care of 21 children and most of the workers are over 60. "They're all retired local housewives."

Yang Lei, who founded a local day care center in Shanghai, said the "tie up" was widely used in institutes and nursing homes across China and it's less scary than the general public would imagine.

"Associated institutes should hire professionals to keep track of patients' medical history before resorting to tying them up, things such as how often do they have epilepsy and the level of schizophrenia should be kept on record," said Yang. She said the purpose of "tie up" was to prevent children hurting themselves and others.

"Another thing is that around 70 to 80 percent of a welfare institute's total operating revenue should go to labor costs to make sure it runs properly for this kind of orphanage," Yang said.

Wu said even if the plan of hiring professional health care staff was put into place, a county-level welfare house could have difficulty attracting qualified staff. Wu also said the welfare house was not going through any financial woes when the "tie up" case happened as "21 children get 180,000 yuan in nursing costs every year from local government apart from the full payment for the workers." The monthly salary of each worker is 730 yuan

Tu Xiaoju, a lawyer specializing in legal aid in Beijing's Changping district, said Cangnan County Social Welfare Institute would not be charged with child abuse as there is no legal provision involving child welfare houses under China's current legal system.

The welfare house promised to transfer all of its 21 children to another local institute next weekend.