HONG KONG — A lawyer who energetically represented Christian churches whose crosses were torn down by the Chinese government has disappeared, probably into police custody, a colleague and supporters said on Friday.

The lawyer, Zhang Kai, is based in Beijing but went missing on Tuesday night in Wenzhou, a coastal city in eastern China where Christians have opposed a government program to demolish church crosses, Yang Xingquan, a colleague of Mr. Zhang’s at the Xinqiao Law Firm in Beijing, said in a telephone interview.

“We’ve heard no official information about his whereabouts,” Mr. Yang said. “He was in Wenzhou when he disappeared on the 25th, but since then we’ve heard nothing from him or about him.”

In a statement on Wednesday, Mr. Yang urged the government in Wenzhou to release Mr. Zhang and his assistant, Liu Peng, who is also missing. Police officers in Lucheng District, Wenzhou, where the two men were last seen, either refused to say anything or said they did not know anything when called.