BEIJING, Nov 17 (AFP) - Once priding itself on its lower crime rates than Western countries, China is witnessing a surge in violence -- including grisly serial murders -- that analysts Monday blamed on ballooning social problems and police failings.

In a five-day period last week, police arrested an ex-convict for 65 killings, a man suspected of strangling 25 high school students, and a couple for murdering 12 women.

The murders highlight a rapidly changing Chinese society in which growing economic inequalities coupled with loosened social restrictions are leading more people to crime, observers said.

Many criminals come from extremely poor backgrounds whose efforts to advance had been blocked by government-imposed obstacles, Frank Lu, director of the Hong Kong-based Information Center for Human Rights and Democracy said.

"These people develop a deep hatred for society," said Lu. "Unless the government addresses these social inequalities, violent crime will only increase."

Twenty years of economic reforms have been accompanied by mass poisonings, bombings, revenge attacks and other violent crimes rarely seen in previous decades.

More troubling, analysts said, the recent murders reflect the fact that China's police see no need to inform the public about serial killers.

"This is shocking. Nobody knew about these crimes until after the police solved the cases," said Lu.

"This is exactly how the Chinese government dealt with SARS initially, which caused it to spread," he said referring to the cover-up of the extent of the Severe Acute Respiratory Syndrome virus in the early days of its outbreak in the spring.

Had police informed the public early about the mass murders, residents might have been able to protect themselves and could have offered police tips, Lu said. The killers may even have been intimidated by the media reports.

"But none of this happened, and the killer was able to carry on killing people," he said.

The man accused of 65 killings over a two-year period was only arrested by chance during a routine inspection of entertainment venues.

And police only began investigating the murder of the 25 high school students in a rural community after the 26th would-be victim managed to escape.

Traditionally, the Chinese government has been afraid to release information that could generate public panic.

Keeping people in the dark "has to do with fear of public perceptions about police capabilities," said Du Xiongbai, a criminology professor at Xiangtan University in central China's Hunan province.

"The police in China believe that if they report the cases before they solve them, it shows they are incompetent."

Crime statistics are not fully revealed and wanted lists are never released. Only solved cases appear on the numerous television programs about crime, which tend to show officers in a good light.

"The government wants to promote a sense of security," Du said.

But such tactics may be having the opposite effect.

"When these major cases are reported, the public wonders how many more cases have not been solved," Du said.

Criminologists and academics are increasingly calling for the government to be more open about crime and crime statistics.

"The government believes these figures cannot be revealed because they reflect to some extent the social problems China is facing, such as the widening gap between the rich and poor," Du said.

"But without these statistics, how can we analyze why crime is going up?"

Du partly blames rising crime on looser controls over state-run media. Nonetheless, media have maintained a hands-off approach to the recent mass-murder arrests, with the 65-murder case garnering fewer reports in the Chinese media than the Green River murders in the US, in which 48 people died.