Toronto police say a third Chinese student reported missing this week is the victim of a scam meant to extort large sums from their families.

Police say Yue "Kandy" Liu, 17, was last seen in north Toronto (near Yonge and Finch streets) on Friday morning.

Two other students, Juanwen Zhang, 20, and Ke "Jaden" Xu, 16, were last seen on Wednesday and Thursday respectively.

Investigators say they are concerned for the safety of the three international students.

They believe the disappearances are linked to a scam in which Chinese students are told to go into hiding and stay off social media or their relatives in China will be hurt.

The families in China are then contacted and told that the student has been kidnapped, and are then asked to pay a large ransom.