A British woman due to be flown out of Wuhan amid the coronavirus outbreak was told to leave behind her three-year-old son because he has a Chinese passport.
Up to 200 UK citizens will be flown out of China on Thursday and put into quarantine for two weeks in the UK.
Natalie Francis, originally from York, said: "I literally had no words when I got the call."
The Foreign and Commonwealth Office said its priority was to keep British nationals and their families together.
Under Chinese jurisdiction, only British passport holders who do not hold Chinese nationality are permitted to leave through assisted departure.
Ms Francis said: "All three of us are in Wuhan at the moment.
"Physically we are fine, but the stress of being locked up for so long... the emotional health is starting to suffer a little bit, especially after this news.
"It's rare you ever feel genuinely helpless, where there is nothing you can do, nothing you can say. It was really upsetting."
Ms Francis, who works as a teacher in Wuhan, said at the start of the outbreak she, her husband, and their son, Jamie, had no plans to leave.
However, over the past few days, she said "we started to panic" after reports younger children were being affected, especially as their son had pneumonia last year.
"My husband said if you get the chance, take Jamie and go home. I don't know who can sort this out."
A Foreign and Commonwealth Office spokesperson said: "The safety of British nationals is our top priority and we have been in close contact with British nationals and their family members who might need help.
"Our priority is to keep British nationals and their family members together and [we] have urgently raised this with the Chinese authorities."