Police have located a body believed to be 9-year-old Emily Branje, who was swept away while whitebaiting at the Hokitika River mouth.

A statement from police said they were alerted to the body, found near the mouth of the Grey River near Cobden on the West Coast, at about 8.30am this morning.

While formal identification is still to be carried out, police say they believe it is Emily, who was swept into the water at the Hokitika River mouth on Thursday September 27.

"Our thoughts are with her family at this tragic time," a spokesperson said.

"We would like to thank all the volunteers and members of the public who assisted in the search for Emily."