Former Chinese University student union president Ernie Chow Shue-fung has fled to Canada with his wife just 10 days after their marriage last month, he announced on Facebook.

Chow said he felt in danger after a middleman approached him two months ago, which he took as a sign authorities had evidence of his role in the Legislative Council siege on July 1, 2019.

"People with a mainland figure behind them asked for a meeting through a middleman, clearly indicating they would like to have a discussion about the Hong Kong Citizens' Deliberative Platform," said Chow, who was secretary of the cross-party platform for cooperation of pro-democracy district councillors before its disbandment.

"I could sense, reading between the lines, they were saying I could remain safe only by betraying others," he added.

Chow did not attend the meeting and fled for fear of getting arrested.

"I am so sorry, my brothers and fellow protesters. I beg your forgiveness for my cowardice," Chow said.

He also said he thought there was a long way to go before his arrest as he stepped down. But after six organizers were among the 47 charged under the national security law for taking part in the camp's primary elections in July, he became concerned.

Chow did not think he could cope with sacrificing his beliefs after listening to the 47's court mention last month.

"Jeremy Tam Man-ho was in tears defending himself. What I saw was an ordinary man trying to face the world with his sincerity and conscience, but he had his dignity completely destroyed by fear the regime induced," Chow said.

This was not the first time he fled, having done so after the start of the arrests of those involved in the 2019 siege. He left to Japan days after the siege but returned in two weeks as he felt sorry to be a "survivor."

Chow, who fled on March 25 this time, said he was able to "find somewhere to live and something to eat" despite leaving in a hurry.

"To others, migration is a search for a better place and an ideal life in a foreign land. For me, migration is to leave the place I love and give up my ideal life there.

"Tastes can be replicated in other places, lifestyles can also be adjusted, but those people, those brothers who begged me to leave Hong Kong, who went through fire and water on the streets with me, can never be replaced or forgotten," Chow added.

"I hope I can keep yelling from the opposite shore and I hope there will be a loud response from my hometown one day."

Ernie Chow

Uni activist flees amid arrest fears