HONG KONG (Reuters) - Hong Kong's airport has seen a second day of chaos, with hundreds of flights suspended or canceled because of pro-democracy protesters, while chief executive Kari Lam warned them against "the road of no return".

The new demonstration comes after China issued increasing signals that the 10-week-old unrest must end and official media broadcast videos showing security forces massed at the border.

The United Nations High Commissioner for Human Rights, Michelle Bachelet, yesterday expressed concern about the use of force against protesters during mass demonstrations in Hong Kong, and called for an impartial investigation.

Bachelet called for an "urgent, independent and impartial investigation" into reports of police use of excessive force against demonstrators, her spokesman Robert Colville told reporters in Geneva.

The rights to freedom of expression and peaceful assembly and the right to participate in public affairs were recognized in the Universal Declaration of Human Rights and the Basic Law of Hong Kong.

But she pointed out that her office had "credible evidence showing that security agents used their weapons in a manner prohibited by international standards."

The UNHCR said, for example, the firing of tear gas canisters "in populated areas, confined directly to demonstrators, with a high risk of death or serious injury."

"The office urgently requests the authorities in Hong Kong to immediately investigate these incidents and exercise restraint, so that the rights of those who express their views in a peaceful manner are respected and protected," she said.

After the resumption of traffic at Hong Kong airport yesterday morning, the day after stopping after the cancellation of the airport management of all flights, the flights returned to stop again.

Registration procedures for passengers departing were suspended yesterday after thousands of black-clad protesters set up checkpoints and used luggage carriers to prevent passengers traveling through security checkpoints.

Pro-democracy protesters blocked passengers departing in a number of lanes at Hong Kong airport, a day after a sit-in forced authorities to cancel all arrival and departure flights.

The airport authority announced that check-in services for flights departing were suspended.

The day before yesterday, crowds of demonstrators, numbering about 5000 people, according to police, the arrival yard at the airport, prompting his administration to make a rare decision to cancel all flights.

Protesters held up banners reading "Hong Kong is not safe" and "shame on the police" at the airport, accusing them of resorting to excessive violence to quell protests.

Yesterday morning, Hong Kong Chief Executive Carrie Lam held a press conference in which she warned of serious consequences if the escalation of violence was not brought to an end.

"Violence, whether it be the use of violence or condoning it, will push Hong Kong on the road of no return and plunge Hong Kong society into a very worrying and dangerous situation," Lam said.

"The situation in Hong Kong last week made me very concerned that we have reached this dangerous situation."

 € رئيس The Chief Executive of Hong Kong warns of serious consequences if the escalation of violence is not stopped.