The US State Department recommends that citizens "raise their awareness" while in China due to the growing risk of detention or ban on exit.

"US citizens may be detained without access to consular support services or provided with information on the charges against which they are alleged," the State Department said today in a scene.

The agency added that US citizens could face "lengthy interrogations and detention" for reasons related to national security.

"Security personnel can arrest and / or deport US citizens for sending private messages that criticize the Chinese government," the warning added, although no specific example was provided.

The Chinese Foreign Ministry has not yet made a comment on the US security alert.

Security warnings have been issued in the context of increasingly strained US-China bilateral relations due to issues, ranging from Covid-19, Hong Kong's new trade and security laws, and accusations of detention of Uyghurs.

Washington and Beijing have also recently "responded" to each other by visa restrictions with officials on both sides, while emphasizing the deteriorating relations between the two countries.

"Relations with China have been severely damaged. They could have prevented the epidemic ... But they did not," US President Donald Trump told reporters on Air Force One while on the road.

The US president also warned that a second-phase trade deal with China is not currently a priority for the US government and he has "many other things" that need more attention.