Shanghai, China - The Chinese authorities have arrested a bishop belonging the underground Roman Catholic Church, a US group says.
The Cardinal Kung Foundation said Julius Jia Zhiguo was taken from his home in the northern city of Zhengding.
Two priests from his diocese - Li Suchuan and Yang Ermeng - were arrested on Monday.
In China, there is a state-sanctioned church for Roman Catholics, but there is also a bigger, unofficial church that is loyal to the Pope.
The foundation said the bishop had refused to cut links with the Vatican and affiliate himself with the state-controlled church.
Earlier this year, both sides jointly approved the appointment of a new bishop in Shanghai in what was seen as an improvement in relations between the Vatican and Beijing.
'Wake-up call'
The Cardinal Kung Foundation said it was the eighth time in two years that the bishop had been detained.
It added that the agents who arrested him in Zhengding, some 240km (150 miles) south-west of Beijing, said they were taking him to a "study session".
Joseph Kung, president of the Stamford, Connecticut-based foundation, said the latest detentions showed that by entering into trading relationships with China, other countries were not improving China's human rights situation.
"This arrest should serve once again as a wake-up call to the fact that some more effective antidote should be employed," he said.
He added that the International Olympic Committee should consider cancelling the 2008 Games in Beijing as "a bargaining chip to improve China's human rights and religious freedom practice".
Taiwan links
China broke off ties with the Holy See in 1951 shortly after the Communist Party took power, forcing congregants to chose between attending state-sanctioned churches, acknowledging Beijing as their ultimate authority, or worshipping in secret.
According to China's authorities the state-sanctioned church has about four million members, while the Vatican says the Roman Catholic Church there has some 10 million worshippers.
China has said it would like better relations with the Vatican, but insists that first the Holy See must cut its diplomatic links with Taiwan.
The Vatican is one of only 25 states that still have links with Taiwan rather than China, and it is the island's only ally in Europe.