United Airlines Holdings Inc. has delayed plans to add extra US-China flights by at least six months, according to a person with knowledge of the matter, as the two nations remain deadlocked over lifting Covid flight caps.  

The increase in flights was originally slated to start late next month, but the move was postponed over the weekend, said the person, who isn’t authorized to speak because the matter is private. The airline has started to inform affected passengers, they added.  

While China has reopened for international travel after the government abruptly ditched its strict Covid Zero policy, the number of flights between the US and the Asian nation is capped at 12 a week per country. That can only be increased with the approval of both governments — a legacy of the pandemic-era restrictions.  

While both countries had been discussing tweaking the flight limit, they were unable to reach an agreement, the person said. United for now has pushed back the restart of a broader range of flights to Greater China until around the end of October. 

A representative for United didn’t immediately respond to a request for comment.

In recent weeks, American Airlines Group Inc. has scheduled an extra two weekly flights from Dallas to Shanghai from the end of March, taking the total to four, according to flight schedule database Aeroroutes. Similarly, an internal memo from Delta Air Lines Inc. showed it will operate twice weekly flights from Seattle and Detroit to Shanghai from early March. utilizing the flight caps on the US side in full. 

Those increases still leave both airlines well below pre-Covid levels  — in February 2019 there was 1,255 flights from the US to China, while there’s been just 48 this month, according to aviation data firm Cirium. 

According to Aeroroutes, United’s latest schedule shows nine pairs of flights from cities including Chicago, Los Angeles, San Francisco, Washington DC and Newark, New Jersey to Beijing, Shanghai, Chengdu and Hong Kong postponed until late October. Some affected passengers have already been notified about the impact to their flights between Newark and Hong Kong, according to an email seen by Bloomberg News.  

By early March, Chicago-based United will operate San Francisco to Shanghai via Hong Kong flights four times a week.  

The number of international flights to and from China was at 17% of pre-Covid levels as of Feb. 19, according to China flight tracker VariFlight.

The US still requires passengers entering the US from China, Hong Kong and Macau to submit a negative pre-flight Covid-19 test result, a rule re-introduced at the end of last year after China’s lifting of Covid Zero policies coincided with a widespread outbreak across the nation.