15/07/2017 8:58 AM AEST | Updated 15/07/2017 8:58 AM AEST

Amber Alert: Desperate Police Search Continues For Missing Sydney Kids

The siblings went missing on Thursday.

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Police are looking for two missing Sydney children.

NSW Police are desperately searching for two Sydney children who went missing on Thursday.

Authorities have issued an amber alert for the two children, Luke Smith and Hayleigh Smith, who haven't been seen for more than 36 hours.

The brother and sister are believed to be with their mother Nicole Boyle, 36, and 50-year-old Neville Kerslake.

They were last seen leaving a home on Willarong Road, Caringbah South, on Thursday about 4.30pm.

"Nicole Boyle is described as being of Caucasian appearance, of large build, about 155cm tall. She has brown eyes and brown hair," police said in a statement.

"Neville Kerslake is described as being of Caucasian appearance, of medium build, about 175cm tall. He has brown eyes with grey hair."

Police said the group may be travelling in a blue 2005 Ford Falcon with NSW registration DNJ 48E somewhere in the southern part of NSW.

Police want the public to report any sightings of the group or their vehicle.