The Chinese authorities have rejected claims by the Vatican that they arrested three Catholic bishops.
Openly practising Catholics must do so in state-approved churches
A spokeswoman for China's Foreign Ministry said the accusation was "totally groundless".
"The Chinese constitution guarantees citizens have the right to religious freedom," she said.
The Vatican had claimed that the bishops of Xuanhua and Zhending, as well as the assistant bishop of Xiwanzi, were recently detained.
It said that while the Zhending and Xiwanzi prelates were released within days, the bishop of Xuanhua, who is 84 years old, had not been heard from since 27 May.
In a strongly worded statement, Vatican spokesman Joaquin Navarro-Valls said the arrests had caused the Holy See "deep pain".
Bishop 'attended course'
"These measures are inconceivable in a country with rule of law, and infringe upon human rights, in particular that of religious freedom," he said.
The Agence France Presse news agency quoted an official at China's Religious and Ethical Affairs Bureau as saying that the bishop of Xuanhua, Zhao Zhendong, had voluntarily attended a course on religious policy which lasted until mid-June.
"Mr Zhao is now performing services in his own church," the official said.
BBC religious affairs correspondent Jane Little says the Vatican's intervention suggests that it has lost patience with China.
Chinese Catholics are split between members of a state-backed church, and others who acknowledge the authority of Pope John Paul II, in defiance of Chinese law.
The Vatican says about eight million Chinese belong to the so-called underground Catholic church, while the state-backed Chinese Patriotic Church has an estimated five million members.
The Vatican and China have had no diplomatic ties since the 1950s, when Beijing ordered Catholics to stop following the Pope.
Critics of Beijing say the authorities have redoubled efforts to suppress the underground Catholic church in the past year, demolishing churches and arresting priests and worshippers.
In December, Beijing dismissed an official American report which had criticised religious intolerance in China.