US Secretary of State Antony Blinken has postponed his trip to China after a Chinese spy balloon flew across the US.

A senior State Department official said conditions were not right at this time for what would have been the first high level US-China meeting there in years.

A Chinese apology was noted, the official said, but described the balloon as a clear violation of sovereignty and international law.

The visit was to come amid fraying tensions between the US and China

America's top US diplomat was set to visit Beijing to hold talks on a wide range of issues, including security, Taiwan and Covid-19.

But there was consternation on Thursday when US defence officials announced they were tracking a high-altitude surveillance balloon over the United States.

While the balloon was, the Pentagon said, "traveling at an altitude well above commercial air traffic" and did "not present a military or physical threat to people on the ground", its presence sparked outrage.

Former US President Donald Trump was among those calling for the US military to shoot it down.

On Friday, China finally acknowledged the balloon was its property, saying that it was a civilian airship used for meteorological research, which deviated from its route because of bad weather.

A statement from China's Foreign Ministry said that it regretted the incident and would work with the US to resolve the issue.

However, the state department official said that while the US acknowledged China's claim about the balloon's purpose, it stood the assessment that it was being used for surveillance.

Another trip by Mr Blinken to China would be planned "at the earliest opportunity" the official said, adding that Washington planned to maintain "open lines of communication" about the incident.

Mr Blinken had been expected to visit China on 5 and 6 February.

A US official quoted by the Associated Press said that the decision to abruptly halt the trip was made by Mr Blinken and President Joe Biden.

Mr Biden did not take questions about the balloon following remarks about the US economy on Friday morning.

According to US officials, the balloon flew over Alaska and Canada before appearing in the US state of Montana, which is home to a number of sensitive military missile sites.

Although fighter planes were alerted, the US decided not to shoot the object down due to the dangers of falling debris, officials said.

Several Republican lawmakers - as well as former President Donald Trump - have criticised the decision and urged the US to down the balloon.

"Shoot down the balloon," Mr Trump said in a short message on his Truth Social social media platform.

On Twitter, House Speaker Kevin McCarthy said that the balloon incident was "a destabilizing action that must be addressed".

While US officials have not commented on the size and details of the suspected spy balloon, Chinese officials have previously publicly expressed interest in the potential military and intelligence-gathering potential of balloons.

"Technological advances have opened a new door for the use of balloons," an article in the military-run Liberation Army Daily said last year.

In 2022, Taiwan's defence ministry said it detected Chinese balloons over its territory.

By Bernd Debusmann Jr
BBC News, Washington