Image copyright AFP Image caption A statement from the hospital said men must have "favourable political qualities"

A Beijing sperm bank has demanded loyalty to the Communist Party from all potential donors.

Peking University Third Hospital said in a statement on its WeChat web page on Wednesday that donors must "love the socialist motherland".

The post also promised 5,500 yuan (£622; $872) to those successful individuals who manage to pass medical tests for fitness and sperm quality.

The statement was later deleted from social media on Friday evening.

It had said that all applicants must be men aged between 20 and 45 and that they must not have any genetic or infectious diseases, or show any signs of weight problems, colour blindness or hair loss.

The men must also have "favourable political qualities", the statement read.

It added that applicants must "support the leadership of the Communist Party, be loyal to the party's cause and be decent, law-abiding citizens, free of political problems".

It is not clear how the hospital plans to verify the ideological loyalty of donors.

A doctor on the hospital helpline told the South China Morning Post: "It would be fine as long as you consider yourself suitable".

Image copyright Reuters Image caption Demand for sperm has surged after China relaxed its one-child policy

China's other sperm banks have not asked for party loyalty from their prospective donors.

Peking University Third Hospital launched the drive for sperm donations on Wednesday, and while the WeChat post has been deleted, it will run until 23 May, AFP news agency reports.

According to China's National Health Commission, there are only 23 sperm banks nationwide - and many have a shortage of donors.

China relaxed its one child policy in 2015, leading to a surge in demand for donated sperm.

In order to use the services of a sperm bank, families must prove the would-be father is infertile or carries a genetic disease.

The campaign has drawn gentle mockery from Chinese social media users, with one WeChat post reading: "Love for the party starts with a sperm."

Another message, on microblogging site Weibo, pointed out: "Acquired traits can't be passed down."