Leung said he had phoned, messaged and emailed Chu over the past two days after receiving his letter requesting help, but Chu’s phone was off.

“No one, no matter what his political stance is and no matter how he takes on different interests in society, can be threatened with illegal or even violent means,” Leung said. “The government will not accept these illegal and violent acts.”

The Post was told that officers were investigating if a rural strongman with triad connections was involved in the threats that prompted police to offer the environmental activist and his family round-the-clock protection starting on Thursday.

Cheung built part of his reputation taking on the powerful Heung Yee Kuk village representative body over land rights in the New Territories.

One source said the threats might have come from a triad gang active in Yuen Long.

“Officers are investigating who ordered the gang to deliver the threat,” he said.

The alleged intimidation might be linked to Chu’s campaign against the use of a plot of land in Wang Chau, Yuen Long, the source said, where the government had to relocate a public housing project in the face of opposition from rural leaders.

It is understood police are also investigating a suspected link to a dispute over an illegal waste dump in Tin Shui Wai.

Another source believed a crackdown on the triad faction suspected was imminent. “The triad faction leader will be our target,” he said.

The winner of the highest number of votes in the geographical constituencies, meanwhile, went to Tung Chung on Friday to thank voters, while his wife stopped going to work and his daughter stayed away from school.

At least five officers flanked him during his hour-long tour around the public housing estate.

“The police arrangement has made me and my family feel safe. But I am concerned about the safety of my team members,” he said.

The lawmaker-elect said he would change his home every day as part of his protection plan and police officers would follow him wherever he went.

“I can’t die – I will keep calm and look for ways to start pushing ahead with our agendas.”

On Facebook live late Friday night, Chu said he had not received the call from the chief executive, saying there might have been misunderstanding.

“I will call him tomorrow and tell him to tidy up the mess he has made for Hong Kong and then pack up and go,” he said.

“We will sweep away the collusions between the government, businesses, rural forces and triads, and we’ll sweep him away too.”

Chu called on people to gather at his street booths in different districts over coming few days to rally against political violence and such collusions. He would also attend the assembly of a Christian group outside police headquarters on Sunday.

While expressing support for Chu, the chief executive rejected another candidate’s claim that he had to pull out of the elections under a threat coming from Beijing. Leung said he “regretted” the allegations made by the Liberal Party’s Ken Chow Wing-kan, dismissing them as “surmise and innuendo”.

Additional reporting by Gary Cheung