An elderly Christian pastor detained by Chinese authorities has had his case taken on by a Beijing-based law firm, religious freedom charity China Aid reports.

Shen Fuchu, 73, who leads a church in Shanghai, was detained for 10 days by authorities in Qiqihar, Heilongjiang province, in September last year. He had been visiting a house church in the city and had gathered more than 70 people in the home of a local Christian. Police raided the meeting, confiscating more than $10,000 dollars given to Shen and another church leader to cover travel costs, and claimed his title as pastor was false because he did not work at a church registered with the Chinese government.

While in custody, Shen had a number of personal belongings confiscated and received a fine.

Beijing's Gongxin Law Firm will represent Shen, who claims that his case was handled unlawfully. A document outlining his lawsuit says that he was threatened while under investigation, and was not allowed to rest, eat or drink.

The document also notes that the Chinese constitution guarantees freedom of religion or belief, and that neither Shen nor his companions violated any laws or regulations.

Lawyers Li Baiguang and Liu Peifu are to take on the case, in addition to those of two other Christains, Zhang Jun and Chen Wu, both of Guiyang in Guizhou. The two are contesting the closure of two buildings used for church meetings.

The Communist Party in China is believed to be becoming progressively more suspicious of the influence of Christianity, which is experiencing significant growth in the country. Up to 1,700 churches have been demolished or had their crosses removed in Zhejiang province, and a number of church leaders and their lawyers have been arrested and detained.