The Hong Kong police have arrested four people, including a 90-year-old Roman Catholic cleric, on suspicion of operating a fund that supported anti-government protesters.

The police announced they detained a former bishop of Hong Kong, Cardinal Joseph Zen, singer-actress Denise Ho and two others. The four were released Wednesday night.

The police say Zen and three others colluded with foreign forces to run a legal aid organization that violates the national security law.

The now-defunct 612 Humanitarian Relief Fund helped those who took part in anti-government protests three years ago and were arrested or injured.

Zen, a prominent pro-democracy activist, has long been critical of Beijing's restrictions on religion. In recent days he had been supporting activists detained or imprisoned in Hong Kong.

Asked about the arrest of Zen, White House Principal Deputy Press Secretary Karine Jean-Pierre told reporters on Wednesday that freedom of expression is critical to prosperous and secure societies.

She called on Beijing and Hong Kong to cease targeting activists and to immediately release those who have been unjustly detained and charged.