Authorities have released new images as they continue the urgent search for three missing children last seen on the Gold Coast on Friday, July 18.

Initial reports state that a 10-year-old girl and a six-year-old boy were last spotted near Mirambeena Drive in Pimpama at approximately 8.50am that day. Both children are described as Caucasian, with brown hair and brown eyes.

Police have since released an additional photo of a seven-week-old baby girl, also missing and believed to be with the other children.

A fourth image released by investigators shows 41-year-old Monique, who is known to the children and is believed to be travelling with them. Monique is described as Caucasian, with dark brown hair and brown eyes.

The group is thought to be travelling in a white Nissan X-Trail bearing Queensland registration 992XPS, and police believe they may now be in the Tenterfield area of northern New South Wales.

Authorities are urgently appealing for public assistance and have asked Monique to make contact with Policelink on 131 444.

Anyone who has seen the children, Monique, or the vehicle is urged to contact police immediately.

Images: Queensland Police