A Chinese Christian writer who wrote extensively about the mass demolition of crosses in Zhejiang province was detained and questioned on Tuesday on suspicion of "inciting subversion of the state", a friend told South China Morning Post.

Zan Aizong, a member of the Chinese Independent Pen Centre, was taken away and his house raided according to his friend, who spoke on condition of anonymity.

Aizong, a Zhejiang-based writer, has written extensively on human rights violations within China whilst also focusing on China's house churches, calling the government to recognise them as legal places of worship.

Last year, Wenzhou, known by some as China's Jerusalem, was targeted by the Zhejiang government. Thousands of churches were victims in a massive campaign under the guise of "demolishing illegal construction."

Up to 1,700 churches in Zhejiang have been demolished or had their crosses removed as part of a three-year 'Three Rectifications and One Demolition' campaign, which scarcely covers the widely understood motivation of combatting the increasing influence of Christianity in the country.

At least 20 Christians are being held in "black jail" in China currently, according to China Aid, mostly from the Zhejiang province. Included in this number are church pastors and deacons, as well as human rights lawyer Zhang Kai, who provided legal advice for churches in their resistance to the campaign.