Beijing - China has launched a crackdown on illegal guns, the government said on Tuesday, as police continued door-to-door searches for the murderer of a soldier in a city notorious for gun trafficking and other organized crime.

The six-month nationwide crackdown is designed to "ensure social stability" by confiscating illegal weapons, preventing gun-related crime and imposing closer supervision over the use of guns, the Ministry of Public Security said.

Local police forces should seize all illegally traded guns and arrest groups or individuals illegally making firearms, the ministry said in a statement posted on its website.

The campaign follows the murder of an 18-year-old soldier who was shot at his sentry post and robbed of his submachine gun by an unidentified attacker on Thursday evening.

Police have offered a reward of 300,000 yuan (44,000 dollars) for information on the attack in the south-western city of Chongqing, which is reportedly one of China's biggest centres for weapons' trafficking.

State media in January quoted a Chongqing police official as saying the city had become "a passageway for illegal firearms trafficking through which guns can spread throughout the south-west or even the entire country unless action is taken."

Wu Lixun, deputy chief of the city's crime squad, told the Chongqing Times that inter-provincial and online gun trading were rising in the city and across China.

Wu led a team that found four illegal arsenals and 10 gun-making workshops in January in Chongqing and the neighbouring provinces of Guizhou and Hunan, the report said.

The city's police handled 339 cases involving illegal firearms last year, about triple the number in 2003, it said.

Chongqing also tried a major organized criminal gang last April, sentencing 19 people for crimes including murder, drug trafficking, robbery, illegal possession of firearms, and bribing police officers.

The city's deputy police chief, Wang Lijun, is "highly regarded for his efforts to stamp out mafia-style gangs" following his earlier campaigns in the north-eastern province of Liaoning, the official China Daily said in November.

State media have also reported criminal gangs in some cities using military weapons and other hardware, even armoured personnel carriers, in recent years. (dpa)