The European Parliament has passed a resolution condemning the recent arrest of 90-year-old Hong Kong Cardinal Joseph Zen.

The resolution urges the Vatican "to give full support to Cardinal Zen" and "strengthen its diplomatic efforts and its leverage on the Chinese authorities".

Reinhard Buetikofer, leader of the European Parliament's China delegation, was quoted by the South China Morning Post as saying, "The European Parliament has stood and still stands and will continue to stand with Hong Kong.

"This parliament continues to actively show solidarity with Hong Kong democrats and against Chinese communist oppression."

Cardinal Zen, the former Bishop of Hong Kong, was arrested in May along with other pro-democracy advocates for supposedly colluding with foreign powers.

The arrests were tied to their involvement in a defunct relief fund that had provided financial assistance to protesters facing legal challenges over their opposition to Beijing's increasing control of Hong Kong. 

The cardinal was detained for a few hours before being released on bail. He is to stand trial in September.

The non-binding resolution, passed on 7 July, said his arrest was "an attack on the freedoms guaranteed in the Hong Kong Basic Law, including the freedom of religion or belief".

It calls for all charges against the cardinal to be dropped.