State Department - The United States has joined the Vatican in expressing concern after Hong Kong police arrested a prominent Catholic cardinal and other pro-democracy activists on national security charges.

Cardinal Joseph Zen, 90, former bishop of Hong Kong, was arrested Wednesday on charges of collusion with foreign forces. He is a fierce critic of the Beijing government. Zen was later released on bail.

"We're increasingly troubled by steps in Hong Kong to pressure and eliminate civil society" and concerned by the clampdown in Hong Kong against those who "speak out both in the media, in religious circles and in academia," said Kurt Campbell, White House National Security Council coordinator for the Indo-Pacific.

White House deputy press secretary Karine Jean-Pierre also weighed in.

"Freedom of expression is critical to prosperous and secure societies," Jean-Pierre told reporters aboard Air Force One. "We call on PRC and Hong Kong authorities to cease targeting Hong Kong advocates and to immediately release those who have been unjustly detained and charged, like the Cardinal Joseph Zen ... and others arrested today."

At the Vatican, spokesperson Matteo Bruni said in a statement that "the Holy See has learned with concern of the news of the arrest of Cardinal Zen and is following the developments of the situation with extreme attention."

A Hong Kong government spokesperson told VOA a statement would be provided as soon as it was available.

Freedom of speech and assembly in Hong Kong have been eroded as the Beijing government has exerted greater control over the former British colony in recent years, say critics.

In a recent report, the State Department denounced actions by Chinese authorities that eliminated the ability of Hong Kong's pro-democracy opposition to play a meaningful role in the city's governance and effectively criminalized peaceful political expression critical of the central and local governments.

In a seminar to preview the upcoming special summit between the U.S. and Association of Southeast Asian Nations, Campbell said the U.S. would continue to have "dialogue and conversations with the interested parties including Great Britain" about the status of Hong Kong.

The senior U.S. official also laid out Washington's goal for a free and open Indo-Pacific region, including stability in the Taiwan Strait.

"The United States wants to take steps to maintain peace and stability across the Taiwan Strait," said Campbell. "We are not seeking to take provocative actions. We want clarity about the desire to deter steps that would be provocative and we believe it's critical for other countries to both publicly and privately underscore that what has taken place in Ukraine must never happen in Asia."