The priests and church-goers from Tianshui belonged to the "underground" Church which is not recognised by China, and had been put in detention centres, AsiaNews said.

Among them was Tianshui's former bishop, Casmir Wang Milu, who the government intends to replace with one of its own candidates from the State-controlled Catholic Church, without papal approval, the agency reported.

Wang Chengli, a priest in the Heze diocese in the Shandong province, was sentenced on Thursday to three years of "re-education through labour," AsiaNews said.

A Catholic source was quoted as saying the priest had been "condemned for his firmness in refusing to subscribe to the Patriotic Association," a reference to the Chinese government's Catholic Patriotic Association.

The Vatican has been locked in a bitter struggle with Beijing in recent months over ordinations they say are illegitimate. Threats of excommunication have gone unheeded by China, which has said it will continue to ordain bishops.

Last weekend's arrests followed a police raid at the end of July on protestants who also belonged to underground churches, according to Catholic news agency Eglises d'Asie.

More than 20 priests and church-goers were arrested on July 26 during a meeting in Wuhai in Inner Mongolia, the agency said, citing religious freedom campaign group China Aid Association.

Six of them were released shortly afterwards on the grounds of age or ill health but another 15 were imprisoned for "cult practises which threaten State security."

Hong Kong's court of final appeal ruled in June that the city's justice system could not be used to sue the Democratic Republic of Congo because of China's position that all sovereign states should be immune from prosecution.

The National People's Congress (NPC), China's rubber-stamp parliament, said it had upheld the ruling.

The NPC ruled that Hong Kong's laws on state immunity must "be consistent with the rules or policies on state immunity that the central government has adopted", said Li Fei, deputy director of the NPC's committee on Hong Kong Basic Law.

The case revolves around US-based fund FG Hemisphere Associates which is reportedly trying to reclaim over $100 million from the Congo in a commercial dispute case. The debts were being held in Hong Kong.

Hong Kong, a former British colony which was returned to Chinese rule in 1997, maintains a semi-autonomous status with its own political and legal system, and guarantees civil liberties not seen on mainland China.

The Basic Law, the city's mini-constitution, provides Hong Kong's government with a high level of autonomy except in defence and foreign affairs, in which Beijing has the final say.

Critics have said the decision by Hong Kong, known for its daily protests and vibrant civil society, to seek Beijing's interpretation on the matter undermines the city's judicial independence.

Eric Cheung, an assistant law professor at the University of Hong Kong, said he "respected" the move but cautioned it will have a "negative effect" on Hong Kong's status and reputation as a semi-autonomous region.

He said the decision could also damage Hong Kong's reputation as an international financial hub, which is the base of many multinational companies.

"This will have an adverse impact on the city as an international trade centre because it will set a precedent for all other businesses that come here in the future," Cheung told AFP.

Supporters of seeking Beijing's interpretation said the move was the right one, as sovereign immunity falls under foreign affairs where Hong Kong has no jurisdiction.