A Chinese girl has been detained by American authorities for over a month after “giving [a] wrong answer to the questions asked by officials at the US border control," said a social activist.

The underage girl who held a tourist visa said her entry purpose was “learning English," which was subsequently questioned by authorities from the US Customs and Border Protection (CBP), said the San Francisco-based activist Yang Haiping.

The girl planned to attend summer camps in October, but it turned out she had to spend her days in a “semi-official” detention center for minors in the US.

“She burst into tears then," said Yang, who the girl has reached out to for help.

Yang also said the detention center had no clue as to how to handle a situation like this, claiming the lawyer was not allowed to meet the girl until he went to the center for the third time.

Officials from the detention center allegedly asked the girl not to engage a lawyer, but to apply for asylum, since the wounded or abandoned underage are qualified to stay in the country through legal ways under the law of the US.

However, the family refused to do so. The girl’s father had been to the US twice in the hope of resolving the problem, but was told that there was "insufficient proof" for her release.

Repatriation is not an option for a case like this, as the girl is not considered an adult who can legally take a flight alone.

While the US has become a popular destination for Chinese tourists in the past few years, worries of entry refusal have been rising under toughened immigration laws of the country.

A friend of Yang was previously refused entry into the US after she had given birth in the country, according to the activist.