BEIJING (Reuters) - A well-known Chinese rights lawyer has appeared on state television confessing to crimes after a months-long disappearance, the latest case in China's widening crackdown on dissent.

Mr Zhang Kai had represented a group of Christians who were detained for suspected financial crimes last year after they resisted the demolition of crosses.

Heavily Christian Wenzhou, in the eastern province of Zhejiang, was the site of protests in 2014 over a government campaign to demolish crosses.

On a news programme on state-controlled Wenzhou TV on Thursday night, Mr Zhang confessed to encouraging Christians to come together to "protect their rights" after the authorities removed crosses from churches.

"I really regret doing these things, I feel very remorseful," Mr Zhang said. "These things violated China's law and violated my personal integrity as a lawyer, and they harmed societal structure and national security."

Police in Wenzhou could not be reached for comment, and Mr Zhang's exact location was not clear.

In October, United States Secretary of State John Kerry said Mr Zhang, who had represented Christian groups, was detained shortly before a planned meeting in August with Mr David Saperstein, the US ambassador for international religious freedom, who was visiting China.

Suspects accused of crimes in high-profile cases are often shown confessing on Chinese state television. Rights groups have said these confessions, which usually take place long before a trial, violate the rights of the accused to due process.

The authorities in the region have said crosses are removed because they violate regulations against illegal structures. Rights groups say demolishing crosses restricts Christianity and religious freedoms.

Communist China officially guarantees freedom of religion though authorities are sometimes suspicious of religious groups.

Experts say there are up to 60 million protestants in China, divided between official and unregistered churches.

A top Chinese pastor came under investigation last month on suspicion of embezzling funds after he publicly opposed a cross removal campaign.