McIver was the third Canadian to be detained by China following the December 1 arrest in Vancouver of Meng Wanzhou, chief financial officer of the Chinese telecommunications giant Huawei Technologies Co Ltd, but a Canadian official said there was no reason to believe that the woman's detention was linked to the earlier arrests.
In a statement, Maegan Graveline, a spokeswoman for Global Affairs Canada, said the department "has been following this case for several years and has been providing consular assistance to the Canadian citizen".
Ltd. Beijing said Ms. McIver had been held under "administrative punishment" for working in the country illegally. The case threatens to add further strain to a tense diplomatic standoff between Beijing and Ottawa.
An appeals court agreed with prosecutors who said Schellenberg was punished too leniently when he was sentenced to 15 years in prison on charges of being an accessory to drug smuggling.
Citing a statement released on the official website of Liaoning Higher People's Court on Wednesday, China's Global Times newspaper reported that "the court will accept and hear the case of appellant Schellenberg at 2:00pm local time Saturday".
According to a Dalian Government news publication, Mr Schellenberg had smuggled "an enormous amount of drugs" into China. Their arrests were seen as a tit-for-tat response to Canada's arrest of Huawei chief financial officer Meng Wanzhou, which Chinese authorities have described as a political act. The last foreigner to be tried for drug smuggling was British national Akmal Shaikh, who was caught in 2007 while smuggling over 4 kilograms of heroin into China.
Prime Minister Justin Trudeau has confirmed that McIver's case does not appear to be linked to that of the other two detainees.
Authorities have released no details of the accusations against Schellenberg. Meng has said she is innocent.