More than 2,200 flights havebeen scrapped on Monday, with Chinese and US destinations being the worst hit, the FlightAware datatracking website says.

US airlines say thedisruption is due to crews testing positive or isolating.

Hong Kong is banning allSouth Korea's Korean Air flights for two weeks, after positive cases among somearrivals.

In all, more than 8,000flights have been grounded over the long Christmas weekend that began onFriday.

Although the number ofcancellations is a small percentage of the total, it is higher than normal andcomes at a time of year when many are travelling to spend time with family andfriends.

In a separate development, US authorities are monitoring dozens of cruise shipshit by Covid cases while sailing in the country's waters, with several of themreportedly denied port in the Caribbean, AFP news agency reports.

Recorded Covid cases arerising sharply around the world, largely driven by the Omicron variant.

Despite early findings thatOmicron is milder than other coronavirus variants, scientists are concernedby the sheer number of infections being recorded.

The majority of the flightscancelled on Monday are those by Chinese companies, according to FlightAware.They include China Eastern, which cancelled more than 420 flights, and AirChina, with more than 190 cancellations.

Airports in Beijing andShanghai appear to be the worst affected, with nearly 300 cancellationscombined. The Chinese authorities have not commented on the issue.

The airport in the northernChinese city of Xi'an is also on the list. More than 13million people in the city have been recently ordered to stay at home asauthorities attempt to tackle a Covid outbreak there.

Meanwhile, the hardest-hitUS companies are United and JetBlue. And Seattle-Tacoma is one of theworst-affected airports.

United warned last week thata spike in Omicron cases had "had a direct impact on our flight crews andthe people who run our operation", with many employees required toself-isolate after coming into contact with those infected. Omicron now is thedominant variant in the US.

United警告Omicron造成的大量感染案例「對在我們事業底下活動的機組人員與民眾會產生直接影響」，有許多員工在接觸感染者後被要求要自主隔離。Omicron如今已成為美國病毒界的主宰者。

But severe weather is also afactor. A blanket of snow delayed flights and disrupted roads in the westernstate of Washington on Sunday, adding to the travel chaos.

In the UK, British Airwaysreported more than 40 cancellations on Monday, according to FlightAware.

Nearly 5.4 million peoplehave died with coronavirus worldwide, according to America's Johns HopkinsUniversity. There have been almost 280 million confirmed cases.