Media reports say hundreds of people arrived on six coaches at about 2am before they damaged the so-called Lennon Wall set up by anti-extradition bill campaigners.
Posters about a pro-government “Safeguard Hong Kong” rally to be held on Saturday were also pasted over the existing memos.
Several big placards with the words “Lennon Tunnel” were also replaced by a Chinese idiom meaning a “peaceful death”, the same words which were used by Chief Executive Carrie Lam when she declared the extradition bill to be dead.
About ten funeral wreaths with pictures of some pro-democracy lawmakers and activists, including singer Denise Ho, the convener of pan-democratic camp Claudia Mo, and the Democratic Party’s Lam Cheuk-ting, were also placed at an exit to the tunnel.
By Friday morning, some of the posters that were put up by the mystery group had been removed, and replaced with more messages against the government.