VATICAN CITY (AP) — A bishop in China's underground Catholic church has reportedly been detained, just as the Vatican has been laying the groundwork for him to step aside as part of a long-sought deal with Beijing over bishop nominations.

The AsiaNews agency, which closely covers the Catholic Church in China, said Bishop Vincent Guo Xijin and his chancellor were taken away Monday, at the start of Holy Week. AsiaNews noted that Guo had disappeared for several weeks last year around Easter as well.

The Vatican has for years been seeking to unite China's underground and official churches to bring the more than 12 million Chinese Catholics ostensibly under the pope's wing for the first time since China and the Holy See severed relations nearly seven decades ago. Worship in China is officially allowed only in state-authorized churches outside the pope's authority.

Recently, the contours of a deal were hammered out under which the Vatican would recognize the seven "illegitimate" bishops in China, who were consecrated without papal consent, ask two underground bishops to step aside and allow the official ones in Mindong and Shantou to become the de-facto Holy See-recognized bishops, a Vatican official told The Associated Press.

Guo agreed earlier this year to the Vatican request to step down and become the auxiliary bishop of Mindong, the official said.

The official, who spoke on condition of anonymity because he wasn't authorized to reveal the content of the negotiations, said the deal was not a "good" arrangement for the Holy See, since it limited its activities. But the official said it was the best the Holy See could get for now.

Going forward, the agreement calls for the pope to be able to "intervene" in future bishop nominations, which the official said amounted to a papal veto over names proposed by Beijing.

The Vatican spokesman didn't immediately comment Tuesday on Guo's reported detention.

Police officials in the city of Fu'an, where Guo is based, as well as the city of Ningde, which oversees Fu'an, said they "did not know" anything about the reported detention.

The deal has been buttressed on the Vatican side by years of goodwill gestures, including favorable coverage in Vatican-affiliated media, Vatican invitations for Chinese participation in scientific and cultural exchanges and a recent symposium at the Jesuit-run Pontifical Gregorian University on Christianity in China.

In the keynote speech Thursday, the Vatican's foreign minister, Archbishop Paul Gallagher, went out of his way to laud China for both the "stable and influential" role it is playing in international relations and its "priceless heritage of culture and civilization."

While much of the West has criticized recent moves by China to remove term limits on Chinese President Xi Jinping and consolidate the Communist Party's control over media, Gallagher highlighted Chinese programs that seek to overcome poverty and drive science and technology developments.

He said he was convinced that "it should be possible to work out the coordinates of an authentic Christian presence in China," even under China's insistence of a "Sinicized" Catholic Church.

Xi and his administration have increasingly emphasized the importance of "Sinicization" of foreign religions to show their fealty first and foremost to the Chinese government and ruling Communist Party. Following a major government reorganization this month, the party's governing role over the State Administration of Religious Affairs that oversees relations with the church in China has been strengthened.

The Rev. Bernardo Cervellera, whose AsiaNews agency has charted the underground dismay at the reported Vatican-China deal, dismissed Gallagher's speech as part of the Vatican's "campaign of courtship" to try to get a deal with Beijing.

He doubted that Beijing would sign, saying some government factions still oppose any agreement because it could set a precedent for other religions.

Of Guo's detention, Cervellera added: "It's very curious that this has happened precisely in the diocese where they are putting in place this famous deal."