Two Chinese airlines have scrapped flights between China and Taiwan, amid a row between Beijing and Taipei over access to air routes.
China Eastern and Xiamen Airlines had planned an extra 176 round trips over the Lunar New Year holiday.
But Taipei has refused to authorise the flights, for which tens of thousands of people have bought tickets.
The stand-off will potentially leave passengers stranded as they try to get home for the year's biggest holiday.
In statements, both airlines said they had no choice but to abandon the flight plans.
The refusal to agree to the extra flights is being seen as retaliation from Taipei, after China opened up several new air routes - which both China Eastern and Xiamen Airlines have been using.
Taiwan said China's actions risked flight safety, and went against a 2015 deal to discuss such flight paths before they came into operation.
They included a northbound route known as M503, which travels up the Taiwan Strait that divides China from the self-ruling island.
But Beijing insisted it had the right to launch the routes, including M503, which it said was "designed by China in cooperation with the United States and other countries" in 2007.
It said there was no danger to safety, and that the routes, which were aimed at easing congestion, would only be used for civil aviation.
Beijing added it had advised Taipei of its plans to use the route, but that it did not require consent.
The incident is the latest spat between the two.
China sees Taiwan as a breakaway province that will eventually be part of the country again, but many Taiwanese want a separate nation.
Reports suggest about 50,000 passengers will be affected by the flight cancellations.
The Taiwanese government has raised the possibility of using military planes to bring back people wanting to go home.
The BBC's Cindy Sui in Taipei says that would-be passengers wanting to travel between the mainland and the island were likely to fly via Hong Kong or Macau.
Alternatively they could choose a Chinese airline or Taiwanese airline that had not been using the new routes, though tickets would be hard to come by, our correspondent added.