Police have initiated a search for a teenage brother and sister, identified as Mukarma, 16, and Muhammed, 14, who are reported to have taken their parents' car early Monday morning and run away. The siblings are considered 'extremely vulnerable' by authorities.

The siblings are believed to have taken a white Toyota Prius, with registration KR10 NTF. The vehicle was last seen traveling on the A40 Oxford Road in Gerrards Cross, heading towards Beaconsfield. There have been no further camera sightings of the car, and the family has not heard from Mukarma or Muhammed since their disappearance.

Mukarma is described as 5 feet 3 inches tall, with a slim build and long, black, wavy hair often worn in braids. She may be wearing a hijab and has a dimple on one side of her face.

Muhammed is described as 5 feet 9 inches tall, Asian, with a slim build and shoulder-length black hair. He frequently wears glasses. Muhammed is described as being 5ft 9in, Asian with a slim build and shoulder-length black hair. He also often wears glasses

Detective Sergeant Gary Walker, leading the investigation, expressed increasing concern for the siblings' welfare. "We are increasingly concerned for the welfare of Mukarma and Muhammed due to their ages, the length of time they have been missing and the belief that they may be driving a car without a licence," Walker stated.

He added, "It is now a critical time in our investigation. By now the children, who are extremely vulnerable, could be anywhere in the country, so we are appealing to the public to come forward with any information or sightings. We are particularly keen to hear from anyone who may have offered them assistance or accommodation in recent days. Any piece of information, no matter how small, could be crucial to our investigation."

Authorities urge anyone who sees Mukarma or Muhammed to call 999 immediately, referencing CAD 2117/17AUG. Information can also be provided anonymously through Crimestoppers at 0800 555 111. The siblings are believed to have taken a family member's car - a white Toyota Prius (pictured) - in the early hours of Monday morning