Police are chasing up reported sightings of missing 15-year-old Mia Cooper.

Police first received a missing person report on Saturday morning, and confirmed that the North Shore teen had not been seen since the evening before.

On Sunday evening, Cooper's mother Tracey Stewart made a desperate plea on social media appealing for any sightings of the missing teen who she had not seen all weekend.

The post went viral on Facebook with more than 44,000 people sharing her message and an outpouring of supportive messages rushing in for the family.

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Detective Senior Sergeant Nadene Richmond, Waitemata North Police, said police were continuing to investigate a missing person's report relating to Mia Cooper.

A team of police based in Orewa were "working on the matter", Richmond said.

"Police are working through inquiries at this stage and we are following up reported sightings of Mia.

"If you have seen Mia Cooper, please contact police on (09) 426 4555."

This is by far the hardest thing I have had to write and we do not want or need anyone’s judgement, gossip or...

Posted by Tracey Stewart on Saturday, 15 December 2018