A passing villager heard their cries and rushed to help. But by the time the flames were put out, the brothers were severely burned.

The boys were rushed to the county hospital and transferred on the same night to a city hospital, which had better facilities.

For a month, it wasn't clear if the brothers would survive their injuries. Their conditions stabilised only after they were sent to a Beijing burn hospital through the auspices of Angel Mom, a charity that helps orphans with medical treatment.

By then, the boys' hospital bills were adding up to about 260,000 yuan (HK$327,000), an astronomical sum for their parents, who are poor rural farmers. Although donations helped to cover most of the cost, doctors in Beijing told their father, Li Kang, that follow-up treatment would cost much more.

In the meantime, the family filed suit against Creative Power Entertaining, the Guangzhou-based animation company behind the cartoon series, as well as Shun Shun's legal guardian.

During hearings at the Donghai County People's Court on June 18, the family's lawyers sought compensation for the medical expenses the boys had incurred so far and for future treatment. In addition, the lawyers also requested that the animation company make a public apology for the incident and to insert warnings to viewers in their future programmes.

One of the family's lawyers, Miao Hongwei, later told reporters that although Shun Shun directly inflicted harm on the two brothers, his actions were the result of his exposure to the television series over a long period.

Lawyers representing the animation company have dismissed the accusations and insisted that Creative Power had done nothing wrong. "[ ] has won many national awards and every step of our production follows government requirements. Therefore, we do not take any responsibility in the case," Zou Wenlong, a lawyer for the production company, says.

Although mainland authorities exercise stringent censorship of broadcast content, the State General Administration of Press, Publication, Radio, Film and Television, the country's top media watchdog, does not require production companies to insert warnings in children's programming or to adopt a rating system as in some Western countries.

"In the TV series, we have repeated scenes of the wolf trying to put the goat into a wok of boiling water and each time the clever goat runs away," Zou adds. "But we have nothing like binding the sheep to the tree and set them on fire. In real life, it's the responsibility of the parents to tell their children what they can and cannot try."

Li Kang, a 42-year-old farmer, says he had no idea that television programmes could be potentially harmful to children. "My kids enjoy watching the TV series. We thought they were safe."

Launched in 2005, has now run 1,000 episodes. Plots typically revolve around the battle of wits between a herd of goats and the wolves which want to eat them.

The main characters are Pleasant Goat, a smart young animal who is always the first to detect danger and see through the wolves' schemes, and the adult Grey Wolf, whose demanding mate, Red Wolf, regularly hits him with a frying pan when he fails to catch the goats.

The series made the state authority's list of 40 outstanding children's animation programmes within months of its debut in 2005, and went on to win many provincial and national awards in subsequent years. Its success on television prompted the producer to venture into film. The first movie in the franchise, , was released in 2009, and broke the domestic box-office record for a Chinese animated film, earning 30 million yuan on its opening weekend. The fourth movie came out last year, earning some 200 million yuan within the first two weeks.

The cartoon also caught the attention of Walt Disney, which in 2010 secured a licence to broadcast 100 episodes of the show on its Disney Channel in 52 countries in the Asia-Pacific region.

Despite the series' popularity, some educators and parents are concerned about how its violent scenes might affect children.

Zhang Hong, an associate professor at the Jiangxi University of Science and Technology studying the impact of cartoons on youngsters, is among the detractors. "I don't think the programme is suitable for young children. After watching Red Wolf hit her husband with a frying pan, for example, girls may do the same at home - being narcissistic, over-demanding and even abusive to family or friends," she says.

Zhang, who has a five-year-old son, believes animation programmes can sometimes lead little children to think that what they see on screen is part of the real world.

"Early episodes [of ] have higher quality storylines. But as it progresses to so many episodes, I feel the producer is more focused on commercial success," she says.

"Our children's channels include lots of cartoons that have almost no story but lots of fighting. It's not practical to expect parents to sit with their children whenever they watch television. The best solution is to introduce a rating system and assign different time slots to show these programmes so that parents would know when to turn off the television."

Better choices include shows such as , a cartoon series about two bears' efforts to fend off a logger trying to cut down trees in their forest. Released last year by a digital animation company with the Shenzhen Huaqiang Group, it became an instant hit across the country.

"Containing little fighting and killing, the programme is both entertaining and beneficial to young viewers," Zhang says.

Ye Lan, chief writer for magazine in Beijing, takes a different view. 's commercial success implies that its creators must be doing something right, says Ye, also a contracted scriptwriter for Disney.

"The humour, simple storyline, and straightforward confrontation between the goats and the wolf are what make the programme so appealing to young viewers."

Ye concedes, however, that the producers may have slipped in their portrayal of confrontation between cartoon characters. "When a confrontation is depicted too realistically or without stretching it to an unbelievable state, children may think they can copy it at home. That's where the danger lies."

A cartoon producer who does not want to be identified argues that the Li brothers' tragedy should not lead viewers to suspect the people creating children's shows.

"We all work with one simple idea, which is to make enjoyable programmes for children. It is unreasonable to make us shoulder so many responsibilities. But I agree that China should introduce a rating system and label programmes for parental guidance if some of the content may mislead children," he says.

Perhaps to address parental concerns in the wake of the burning incident, the state watchdog issued an urgent circular on June 27 requesting all media regulators to step up screening of violent scenes in children's cartoons.

Meanwhile, as governments, experts and concerned media companies tussle with the issue, the young victims and their family must wait.

The Li brothers, who each underwent six operations in Beijing, recently returned to Mawang village to continue their recovery.

But the years ahead will likely be just as precarious.

The Donghai county court has yet to rule on the Li family's compensation claims. But Li Kang had sold all the family's crops in order to pay for their medical bills before the boys were rushed to Beijing and has been trying to sell their farm house to raise funds.

"I don't know what else I can sell to find money for the future treatment of my boys," he says.