For American and European travelers, the options of flights in and out of China are narrowing by the day.

Virgin Atlantic, the British airline, said Flight VS251 on Saturday would be its last one connecting Shanghai to London, suspending a route that it first operated 25 years ago. LOT Polish Airlines will suspend its Warsaw-to-Beijing flights after Thursday, while the Scandinavian airline SAS said it planned to halt direct flights between Copenhagen and Shanghai next month.

When China lifted its strict Covid-19 restrictions in 2022, the expectation was that business travel would rebound to prepandemic levels with executives returning to the country, the world’s second-largest economy, in droves. But that hasn’t materialized.

Over the last several months, many international airlines have suspended or reduced the frequency of flights in and out of China. For European and British carriers, the ongoing war in Ukraine has prevented non-Chinese airlines from flying over Russian airspace. This means longer travel times for passengers and inflated costs for airlines forced to take a longer route.

“Significant challenges and complexities” on flying in and out of China contributed to Virgin Atlantic’s decision to suspend its London-Shanghai route, its only China flight, the airline said in a statement. The company noted that avoiding Russia airspace has added one hour to its Shanghai-bound flight from London and two hours going the other way, requiring additional spending for fuel and crew.

The increased costs deliver a heavier blow, because the flights to China are not teeming with passengers. The sluggish Chinese economy and a growing unease from foreign companies about operating in the country has crimped demand for work trips, and tourism has not made up the difference even though Beijing has dropped visa requirements for more than a dozen countries.

In the first half of the year, China said, the number of foreign visitors to the country was 14.6 million. That was a significant increase from the same period a year earlier but well off the pace set in 2019 of 49 million visitors for the full year.

“If the demand was OK and you can offset it with a bit of revenue, then it’s a different ballgame,” said Mayur Patel, a regional sales director for OAG, a global air travel data provider. “But that’s not the case.”

Many European carriers are doing well on flights to Japan, which is also affected by restrictions on flying over Russia. However, many of the flights to Japan are full of tourists.

As European carriers struggle with the economics of flying to China, Chinese airlines are filling the void. They have a significant competitive advantage — offering customers cheaper tickets and shorter travel times — because they continue to fly over Russia without any restriction.

Chinese airlines are aggressively adding to the capacity of flights to Europe. In November, Air China has 24 percent more seats available for European flights compared with the same month in 2019, according to OAG. China Eastern Airlines next month will have 52 percent more seats and Hainan Airlines will have 89 percent more seats, compared with European flights five years ago.

It’s a different picture for major European carriers, which are offering significantly fewer flights than before Covid. The German carrier Lufthansa, Air France and KLM Royal Dutch Airlines have each reduced the number of seats available in November by more than 40 percent compared with prepandemic levels, according to OAG.

Carsten Spohr, Lufthansa’s chief executive, said at a news conference last week that all flights into Europe should be forced to avoid Russian airspace to ensure “a level playing field.” He said being able to fly over Russia provided “enormous advantages to Chinese carriers.”

LOT Polish Airlines said it had canceled its Beijing-Warsaw route over the winter because of “unsatisfactory booking results and a significantly weaker competitive position.” While it did not specify that Chinese carriers had gained the upper hand, it did cite competitors using “shorter routes.” LOT said it planned to resume flights to Beijing in the summer.

When British Airways announced over the summer that it would halt flights to Beijing after October, Chinese students studying abroad said this would make it even more challenging to find suitable flights home.

“How can overseas students in the U.K. return to China?” one user wrote on Xiaohongshu, a Chinese app similar to Instagram. She noted that the challenge to find flights was more daunting for students living in British cities other than London.

There are other considerations aside from Russian airspace.

Citing low demand, the Australian airline Qantas suspended its Sydney-Shanghai flight in July. U.S. carriers are also pushing to keep a reduced flight schedule to China. It’s an indication of how geopolitical tensions between Washington and Beijing and the slumping Chinese economy has weighed on travel.

Last month, United Airlines, Delta Air Lines and American Airlines each filed requests to the Department of Transportation seeking special waivers to continue delaying resumption of their full allocation of flights to China. United, Delta and American said they only planned to operate one-third of their weekly flights between China and the United States during the winter months.

“U.S.-China passenger demand has not recovered to prepandemic levels,” American Airlines wrote in its motion. Delta said it might need additional waivers in the future because of the “challenges” of the Chinese market.