Two Americans, who run an English-teaching business in China, have been detained in the east of the country, according to their company, which said they were being held on "bogus" charges.

Jacob Harlan, a father of five, and Alyssa Petersen were nabbed in Jiangsu province last month, their Idaho-based company China Horizons said on its Facebook page.

A gofundme.com page set up to raise money for Petersen's legal fees says she was formally charged with "illegally moving people across borders".

The detentions come amid diplomatic and trade tensions between China and the United States.

"We are aware of the detention of two US citizens in Jiangsu, China and the charges being brought against them by the provincial government," a US State Department official said on condition of anonymity.

"We take seriously our responsibility to assist US citizens abroad and are monitoring the situation."

China Horizons said on Facebook last week that the pair "are being charged for bogus crimes and their families are working on getting them international lawyers to help them get back home to the States".

Harlan, the founder of China Horizons, was being held in a hotel under police surveillance in the city of Zhenjiang, according to a separate gofundme.com page set up for his legal fees.

Police detained him while he was with his eight-year-old daughter at a hotel in Weifang, Shandong province, on September 28 and took away his phone and computer, according to the post.

His daughter was finally allowed to briefly call her mother she later took an international flight with a family friend.

Petersen, who is the associate director of China Horizons, was detained around September 27 and was not heard from for two weeks until the State Department located her, according to her gofundme.com page.

"We received information that she is doing okay, She wakes up when told, she goes to sleep when told. She spends her day in a Jail Cell or walking in a circle counting steps," the gofundme.com page says.

"She cannot have any contact with anyone outside of a Consulate Officer who can visit once a month and a Lawyer."

The State Department official confirmed that Petersen is receiving "all appropriate consular services".

Contacted by AFP, Zhenjiang police said they had no immediate comment. The US embassy did not immediately reply to a request for comment.

China Horizons, which arranges for Americans to teach English at Chinese schools, said it would shut down at the end of October.

"Unfortunately, because of increasing political and economic problems between the US and China, we are no longer able to send teachers to china safely," the company wrote on its Facebook page.