HONG KONG — Hong Kong police arrested well-known activist Joshua Wong and another core member of a pro-democracy group Friday, and authorities denied permission for a major march in what appears to a harder line on this summer’s protests.

The organizers of Saturday’s march, the fifth anniversary of a decision by China against allowing fully democratic elections for the leader of Hong Kong, said they were calling it off after an appeals board denied permission. It was unclear whether some protesters would still demonstrate on their own.

Police have been rejecting more applications for rallies and marches, citing violence at or after earlier ones. They also are arresting people for protests earlier this summer.

Andy Chan, the leader of a pro-independence movement, was arrested at the airport Thursday night. Three others were taken in earlier this week for the vandalizing of the legislature offices on July 1.

“The first priority of the Civil Human Rights Front is to make sure that all of the participants who participate in our marches will be physically and legally safe. That’s our first priority,” said Bonnie Leung, a leader of the group. “And because of the decision made by the appeal board, we feel very sorry but we have no choice but to cancel the march.”

Police said that Wong and Agnes Chow are being investigated for their role in a June 21 unauthorized protest outside a police station. Both face potential charges of participating in the demonstration and inciting others to join it. Wong also is being investigated on suspicion of organizing it.

Wong is secretary-general of Demosisto and Chow is a prominent member. He was one of the student leaders of the Umbrella Movement, the major pro-democracy demonstrations in 2014.

Isaac Cheng, the vice chair of the group, said the arrests are an attempt to spread fear and “white terror” among Hong Kong residents.

He accused authorities of trying to identify leaders in a “leaderless” movement that has rocked Hong Kong for nearly three months. The Communist Party-ruled government in Beijing is pulling the strings and has misjudged the situation, he said, urging residents to continue protesting despite the risk of arrest.

Demosisto first reported the arrests on its social media accounts, saying Wong was pushed into a private car as he was heading to a subway station around 7:30 a.m. and has been taken to police headquarters. It later said Chow had also been arrested, at her home.

Wong was released from prison in June after serving a two-month sentence related to that protest. He has been speaking out regularly in support of the pro-democracy protests that have racked Hong Kong this summer.

The protests were set off by extradition legislation that would have allowed suspects to be sent to mainland China to face trial and expanded to the general concern that China is chipping away at the rights of Hong Kong residents.

The extradition bill was suspended but the protesters want it withdrawn and are also demanding democracy and an independent inquiry into police actions against protesters.

Police said that Chan was arrested under suspicion of rioting and attacking police.

By KEN MORITSUGU Associated Press