The mother of Vancouver-based pop star Wanting Qu has been arrested on corruption charges in China.

Qu is the girlfriend of Vancouver Mayor Gregor Robertson, who said Friday that the situation was "very tough."

"Obviously it's a personal issue for her," Robertson said. "And it's been many months with no information, and that's very tough. I have next to no information."

Robertson confirmed that Qu Zhang Mingjie was being held in detention in China.

On Friday, Wanting Qu posted a message on her Facebook page expressing her sadness.

"I love my mom dearly and I am truly heartbroken," the post states. "This ordeal is very stressful and I find myself ... crying over it daily.

"I appreciate the love and support from my friends, my fans and my family. I will use your strength to get through these tough times."

China Daily reports that her mother, Qu Zhang Mingjie, a Harbin city official, was arrested after allegedly undervaluing state assets for sale.

According to the South China Morning Post, Qu Zhang Mingjie was dismissed from her position as deputy director of Harbin's development and reform commission in September 2014.

Wanting Qu's relationship with the Vancouver mayor made headlines earlier this year. Robertson had announced his split from his wife, Amy, last summer.

Robertson has attributed his following on Chinese microblogging site Weibo, in part, to Qu, who has hundreds of thousands of followers on the site.