US President George W. Bush has expressed concern over the recent detention of a Catholic bishop in Beijing. Shi Enxiang, 79, an underground bishop from Yixian, Hebei province, was arrested on April 13 in Beijing. Catholic sources said Shi was visiting his sister in the capital at the time. The elderly bishop has been in hiding since escaping from custody in 1996. He recently went to Beijing to stay with his sister. In an interview with the Washington Post on Tuesday, Mr Bush said he was distressed to learn about Shi's arrest. 'That's not a good sign at all,' Mr Bush said. 'And they will hear that from our administration.' China last week defeated a motion by the US to table a resolution at the United Nations Human Rights Commission to put China's human rights records under scrutiny. Yesterday, the Catholic news agency Ucan also reported that another underground bishop had been arrested. Bishop Matthias Pei Xiangde of Beijing was arrested in early April. Pei, 82, does not belong to the state Catholic Church and normally preaches in private homes. The agency said more than 20 Catholics - including the two elderly bishops - had been arrested in recent months in areas where 'underground' Catholic communities were active.