A six-year-old boy with autism named Arian is missing in Bremervörde, northern Niedersachsen, and has been for four nights.

German police have adopted a new 'quiet strategy' for the search, consulting with an autism expert to refine their approach.

The intensified search includes 250 soldiers, night vision and heat cameras, a Tornado plane, drones, and a helicopter, focusing on the Elm area and the Oste river.

Local residents have been asked to check hiding places on their property, while the fire department searches sheds, garages, and manhole covers.

Waste collection has been halted to investigate the possibility of Arian hiding in a trash container.

With near-freezing temperatures and Arian only in a sweater, sweatpants, and socks, the situation is becoming increasingly urgent.

Police have established a hotline for tips and are urging the public to report any information that could lead to Arian's safe return.