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

Phan "Sandy" Phan-Gillis 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.

The San Francisco-based human rights group Duihua said Tuesday that it was the first time that the working group had deemed an American citizen to have been arbitrarily detained by China.

Ban is scheduled to meet Chinese President Xi Jinping and Premier Li Keqiang this week.