BEIJING >> A U.N. panel says China has arbitrarily detained an American woman in violation of international human rights norms, bringing her case back into public attention ahead of a visit to Beijing by U.N. Secretary General Ban Ki-moon this week.

International business consultant Phan “Sandy” Phan-Gillis, 56, has been in detention in China for more than a year, accused of stealing state secrets.

The U.N. Working Group on Arbitrary Detention says she hasn’t been brought before judicial authorities or given access to legal assistance, in an opinion released last week.

The San Francisco-based human rights group The Dui Hua Foundation said today that it was the first time that the working group in its 25-year history had deemed an American citizen to have been arbitrarily detained by China. A detention is deemed arbitrary if it has no legal basis or legal rights are ignored.

Ban is scheduled to meet President Xi Jinping in Beijing on Thursday and Premier Li Keqiang on Friday, though it isn’t clear if Ban plans to raise Phan-Gillis’ case in talks with the leaders.

The U.N. working group says that the Chinese government told it that Phan-Gillis is charged with “assisting external parties to steal national intelligence.” The U.N. group called for her to be released or given proper assistance by a legal counsel.

China’s foreign ministry spokesman Hong Lei, in a faxed response to questions, said: “All of Sandy Phan-Gillis’ rights have been fully guaranteed, and she has been treated well.” He urged the U.N. working group to “perform its duties impartially, respect China’s judicial sovereignty and stop groundless accusations against the relevant Chinese authorities’ lawful handling of the case.”

The U.S. Embassy in China had no immediate comment.

Phan-Gillis, a Vietnamese-American of Chinese descent, often worked as an intermediary in ventures between Chinese and U.S. business interests.

She was detained in March 2015 during a visit to China as part of an American trade delegation that was promoting business opportunities in her hometown of Houston, Texas. She disappeared from the rest of her group in the southern city of Zhuhai at the international border crossing into Macau.

For the first six months she was held under residential surveillance — a coercive measure that allows for people suspected of endangering state security to be held at an undisclosed location. Then she was formally arrested and moved to a detention center in the southern city of Nanning.

The U.N. report included submissions from an unnamed source, who alleged that Chinese authorities flouted the country’s own laws, including failing to notify Phan-Gillis’ family that she had been detained.

The U.N. Working Group on Arbitrary Detention “has, over the years, ruled that the Chinese government has arbitrarily detained scores of its own citizens, but this marks the first time it has ruled that agents have arbitrarily detained an American citizen in violation of international human rights law,” John Kamm, executive director of The Dui Hua Foundation, said in a statement.