Eliza and Henrietta, both aged 32, were last seen on CCTV on Market Street at Victoria Bridge, Aberdeen, around 2:12am on Tuesday, January 7.
They crossed the bridge and turned right onto a footpath next to the River Dee heading in the direction of the Aberdeen Boat Club before vanishing.
The River Dee is the primary focus of searches due to no evidence of the women leaving the immediate area.
Police Scotland have used special resources such as helicopters, dog branch and the marine unit, along with emergency service partners to assist in their search.
Police will remain at the scene while the search widens further, now stretching as far as the coast towards the Port of Aberdeen’s South Harbour, and towards Duthie Park.
Officers are working with authorities in Hungary, where the duo were born, to support relatives.
Eliza and Henrietta are both described as white and of slim build with long, brown hair.
Chief Inspector Darren Bruce said: “Eliza and Henrietta’s family are understandably extremely worried about them and we are working tirelessly to find them.
“We are seriously concerned about them and have significant resources dedicated to the enquiry.
“We are again urging the public to come forward with any information relating to Eliza and Henrietta’s whereabouts.
“The focus of our search remains the River Dee and I would again ask, if you were in the area at the time, please think back, did you notice anyone matching their description?
“Even if it doesn’t seem significant, please pass any information on and let us be the judge of that.
“I would again urge businesses in and around the South Esplanade and Menzies Road area to please review their CCTV footage for early morning on Tuesday, 7 January, 2025 and contact us if it holds anything that may be relevant to our investigation.
“We are also keen to hear from anyone with dashcam footage from that time.
“Anyone with any information is asked to contact 101 quoting incident number 0735 of Tuesday, 7 January, 2025.”