Two construction workers were killed and dozens injured when part of a luxury hotel being built in Myanmar's second city of Mandalay collapsed, sparking a desperate 30 hour bid to free a man trapped in the rubble, police said Monday.

Rescue teams worked round-the-clock to free the trapped 18-year-old worker after the incident on Saturday afternoon at the construction site, according to local police, finally pulling him from the rubble late Sunday.

Myanmar police have arrested more than 90 people for human trafficking offences this year, media reported Monday, but no cases have been uncovered in Rakhine state where persecuted Rohingya have fled in droves.

Police gave a breakdown of their anti-trafficking activities with 56 cases recorded between January and May, the Global New Light of Myanmar reported, citing police captain Min Naing.

Around 500 people including dozens of Buddhist monks protested near the Chinese consulate in Myanmar's central city of Mandalay on Saturday demanding the closure of a flashpoint copper mine.

It was the largest protest since the fatal shooting of a woman demonstrating against the Letpadaung mine in the northwestern town of Monywa -- a Chinese backed venture dogged by complaints of land grabbing and environmental damage.