Hong Kong leader Carrie Lam has warned protesters that their actions could cause a swift and prolonged economic decline, as a weekend of new demonstrations kick off.

Ms Lam said she spoke with business leaders who expressed concern about the long-term effect of the protests, with one businessperson likening the unrest to an economic “tsunami.”

According to the chief executive of the Chinese semi-autonomous territory, the economic effect threatened to be worse than the 2003 SARS outbreak or the 2008 financial crash for the city.

“Compared to the economic downturn caused by SARS that we handled previously, even to the (2008) economic crisis, the situation this time is more severe,” she told reporters.

The effects of the mass protests, Ms Lam said, have hit the Hong Kong economy harder than the 2008 SARS epidemic

Flanked by business leaders, Lam told the media that downward economic pressure had hit like a “tsunami”.

She added that she was worried about the long-term economic consequences of the protests.

Her comments came as hundreds of demonstrators, mostly wearing black shirts, started to gather at the arrival area of Chek Lap Kok Airport earlier on Friday – the second time they brought their message to the international travel hub.

Demonstrators promoted it on social media with a mock boarding pass reading “HK to freedom” and “warm pick-up to guests to HK”.

READ ALSO: HONG KONG PROTESTERS BEGIN THREE-DAY PROTEST AT AIRPORT

The protests, which began in April, opposes a proposed extradition bill which allows criminals to be extradited to mainland China.

READ ALSO: HONG KONG PROPOSED EXTRADITION BILL DECLARED DEAD, PROTEST TO CONTINUE

Extra security measures have been put in place at the airport before the latest rallies, with authorities preventing anyone without a boarding pass from entering the check-in area.

The gatherings across the city, expected to run over three days, have not been authorised, but the last demonstration at the airport passed off peacefully without causing flight disruptions.

Airport Authority Hong Kong earlier said that it was aware of the planned rallies but “the airport will operate normally”.

Meanwhile, an email attributed to an unidentified government spokesman said the government and the travel industry were working to minimise disruptions and “all stand ready to welcome and assist visitors to Hong Kong any time”.

But on Thursday, the government conceded that tourist arrivals dropped 26 percent at the end of last month compared with last year and continue to fall in August.

The travel industry accounts for 4.5 percent of the financial hub’s economy and employs about 250,000 people, or about seven percent of the total working population.

The weeks of demonstrations pose the biggest threat to Beijing’s authority since Hong Kong’s handover from the British in 1997.

And as protests have become increasingly violent, several countries have upgraded their travel warnings for Hong Kong, with Washington this week urging its citizens to “exercise increased caution”.