Police confirmed only five child abductions last year, with three killed, but Thursday's cases show it is not a new problem. Two of the four cases happened last year, but the other two were in 2006 and 2008.

A government official who works closely with police has said that as many as 23 children were kidnapped in Shenzhen last year.

On Thursday, prosecutors told the court that the eight kidnappers, many of them acquaintances of the victims' parents who the children trusted, either dragged the children into vans outside primary and high schools or lured them to their homes.

In the latest sentencing, kidnapper Kong Jinling was sentenced to death and his two brothers-in-law jailed, one for life and one for three years.

The 11-year-old son of a village neighbour was murdered in November.

The boy was abducted outside his primary school and his dismembered body was found the next day, even though his parents had agreed to pay a portion of the 1 million yuan (HK$1.13 million) ransom Kong demanded.

The three kidnappers were also ordered to pay 560,000 yuan to the victim's parents.

The boy's father, Chen Sicai, said he was not satisfied with the sentences.

The three-year jail term one kidnapper received was too light, he said, and police were to blame for the death of his son after they failed to warn of the danger his child was in.

Another kidnapper was sentenced to life imprisonment, and two accomplices were given 15-year jail terms, for kidnapping a 13-year-old outside a high school in October and demanding a ransom of 1 million yuan. Police from Changsha , Hunan , later rescued the boy.

Xu Qingxi was executed for kidnapping a 13-year-old schoolboy and choking him to death in May 2008. The court was told that Xu had worked as the boy's tutor. He had also demanded a 1 million yuan ransom.

The other executed kidnapper abducted a six-year-old girl in March 2006 and killed her by sealing her mouth with tape.

The intermediate court has heard at least five child kidnapping cases this year, following a spate of abductions for ransom since October.

The four cases heard on Thursday were not publicised when they occurred and parents accused the police of failing to inform them of the danger their children faced.

In January, two men pleaded guilty to abducting and murdering a schoolboy in April last year but the court did not hand down a verdict after a three-hour hearing.

Last month, Shenzhen police announced they had arrested 17 suspects involved in at least 51 attempts to swindle families by falsely claiming their children had been kidnapped.

Stolen youth

Shenzhen has seen a surge in kidnapping cases in recent years

An official says the number of children kidnapped in the city last year was: 23