A court in western China has upheld death sentences against two leaders of a gun-running racket that reached into neighbouring Pakistan, state media reported on Wednesday.

Last October, Ma Zeying and Zhang Chenming were sentenced to death by Haidong District Court in China's Qinghai province for illegally buying, shipping and selling guns in China's biggest gun-running case.

It said the gang bought 914 guns and 1,556 gun parts in Pakistan and several provinces and regions in western China to "conduct illegal transactions".

The Qinghai Provincial People's High Court also upheld suspended death sentences on Zhang Guoming, Ma Shenghun and five members of the racket. Two more were jailed for life and five others were given fixed jail terms, the report said.

Guns have generally been hard to obtain in modern China, but Chinese police have previously blamed poverty in China's remote western provinces for fuelling their illegal manufacture and sale.

In a crackdown from June to August, police seized 117,000 guns and detained close to 50,000 people, 1,000 of whom were prosecuted, China's Public Security Bureau said in September.

Separately, the king-pin of a 20-member organized crime gang in China's commercial hub of Shanghai has been sentenced to death for drug trafficking, assault and illegal possession of weapons, Xinhua reported on Wednesday.

Li Bin, who had previously served six sentences for crimes including theft and possessing counterfeit money, had "formed a mafia-style crime ring by hiring unemployed people and ex-convicts" and "made a fortune through drug dealing and an underground gambling business", Xinhua said.

The verdict comes amid a scandal implicating a string of senior Shanghai officials and businessmen, including the city's Communist Party chief, in the misuse of the city's social security fund.