A police diver swept the floor of the river next to the Anglers Tavern in Maribyrnong for signs of the missing mother, who was last seen on June 29.

Detective Senior Sergeant Craig Rhodes, who heads the missing persons unit, was on site as two police divers suited up to search the river bed for weapons or other items linked to the 47-year-old's disappearance.

Saturday's search follows a river search that took place in the same location on Friday afternoon involving members of the water police.

This was the first time divers have been involved.

"This is a follow-on from information we received from the public during the week," Sergeant Rhodes said.

"As a result the divers are now looking as well."

The search focused on a section of the Maribyrnong River nearby the Raleigh Road Bridge. It measures about four metres deep and was a chilly 12 degrees on Saturday morning.

The operation lasted for less than an hour before it was called off.

No items were retrieved.

A handful of passers-by stopped to take in the action on Raleigh Road bridge. But most continued on their way.

Police have been a constant presence in the area ever since Mrs Ristevski went missing about a month ago.

Victoria Police set up an information caravan and doorknocked around Mrs Ristevski's home on Wednesday, searching for new leads.

Detective Inspector Stephen Dennis from the Missing Persons Squad said on Wednesday the investigation was ongoing and police were hopeful of finding Mrs Ristevski alive.

"We are treating this as a missing person case but the longer she remains missing the more difficult it becomes," he said.

Investigators have refused to say if they have any suspects in the case.

Mrs Ristevski, 47, is described as 160 centimetres tall, with a slim build and shoulder-length brown hair.

Her bank account and phone have not been used since she went missing on June 29.

She was last seen wearing a black jacket and jeans and it is believed she had a Coach handbag and purse with her.