Authorities have detained a 79-year-old bishop, seven priests and 13 followers of China's underground Catholic church, a U.S.-based lobbying group said Monday.

The arrests, which occurred throughout the country, were made around Easter, the foundation said.

Bishop Cosmas Shi Enxiang was arrested while visiting Beijing on Good Friday, April 13, according to the Cardinal Kung Foundation. The Stamford, Conn.-based foundation supports China's underground church and monitors government efforts to suppress it. The bishop had been hiding from police since 1996.

Vatican Radio, citing Vatican missionary news service Fides, reported that Mattia Pei, an 82-year-old bishop in China's underground church, was also arrested in early April. It did not provide more details.

China broke ties with the Vatican in 1951 and demands that Catholics worship only in churches approved by the China Patriotic Catholic Association, a state-controlled body that does not recognize papal authority.

Many Chinese Catholics, however, remain loyal to the pope and risk arrest by worshipping in unofficial churches and private homes. The state church claims 4 million believers. The foundation said the unofficial church has 12 million followers. Many believers and some priests move between the two churches.

Police said Monday they had no knowledge of the detentions. The government's Religious Affairs Bureau directed inquiries to its publicity department where phone calls rang unanswered.

Shi has spent nearly 30 years in jail, most recently from 1990-93, the foundation said. It described him as the underground church's bishop of Yixian, a city in central China's Hebei province where the unofficial church is particularly active.

Shi formerly served as the official church's auxiliary bishop of Yixian.

The other arrests listed by the foundation were:

On April 13, authorities detained priests Feng Yunxiang, in coastal Fujian province, and Liao Haiqing, 70, along with 13 followers in southeastern Jiangxi province.

On April 15, authorities arrested Lu Genjun, 39, and three other, unidentified priests in Baoding, Hebei.

On April 19, four days after Easter, authorities arrested Li Jianbo, 34, in Inner Mongolia.

Also this month, a priest identified only as Father Yin, who was arrested in January, was sentenced to three years in a labor camp, the foundation said.