BEIJING - Violent crime is generally on the decline in China, but poorer, more remote inland and border areas still have a problem, police officials said on Tuesday.

From June to August, police seized 117,000 guns, 3.4 million bullets, 1.3 million knives and some 2,500 tonnes of explosives, said Yan Zhengbin, deputy director of the police's security management division.

"We can see that the problem of explosives, guns and knives is concentrated in areas where explosives are commonly used, while the gun problem is mainly seen in outlying mountain and grassland areas," Yan told a news conference.

"In Beijing, Shanghai and other large cities crimes using explosives or guns are extremely uncommon," he added. "The overall trend is of a large fall."

Police detained close to 50,000 people during the crackdown, about 1,000 of whom were prosecuted, Yan said.

He singled out certain parts of China as having more serious problems with violent crime, including the inland provinces of Shanxi, Henan and Hebei, where a well-developed mining industry makes explosives easy to obtain.

Knife attacks have become a particular problem in a country where crime has boomed along with the economy for the past two-and-a-half decades, threatening government control and stability.

Cities in the southern coastal provinces of Guangdong and Fujian -- which traditionally have had problems with gangs like the triads -- were another focus of the crackdown, Yan said.

He said that police in Guangdong's Chaozhou city arrested six people for trying to sell more than one tonne of nitroglycerine, an explosive liquid used in dynamites.

Guns have generally been hard to obtain in modern China, though that has not stopped people from making them themselves.

In 2003, two people from the remote western province of Qinghai received long sentences after being found to have made over 100 guns and 500 bullets, which they had planned to sell.

The police have previously blamed poverty in places like Qinghai for helping fuel the boom in home-made guns, which can sell for more than twice the average monthly income.

People who illegally trade guns in China can be sentenced to death.