06/06/2017 8:22 AM AEST | Updated 06/06/2017 9:35 AM AEST

Australian Woman Sara Zelenak Still Missing After London Attack

The 21-year-old disappeared at London Bridge on Saturday.

Fears for missing Australian woman Sara Zelenak are growing after she reportedly disappeared during the terror attack at London Bridge on Saturday night.

Zelenak was separated from her friends during the attack and her family has not heard from her since, the ABC reports.

Pri Gonçalves is a friend of Zelenak and was reportedly out with the young Australian at the time of the attack.

"We both got curious and went back a few steps to see what had happened when people started running and shouting 'run'. At that moment I got scared and desperate so I ran," Gonçalves told Fairfax Media.

"Sara was with me when people started running and shouting but at that very moment we got separated."

Prime Minister Malcolm Turnbull addressed reports of Zelenak's disappearance on Tuesday morning, and reiterated that another unnamed Australian is also missing in London.

"We have real concerns," he said.

"We are working diligently in London with the police and other authorities there and of course staying in very close contact with their families as we seek to confirm the circumstances relating to those two Australians."

It has not been confirmed if Zelenak is missing as a result of the London Bridge attack. The Department of Foreign Affairs and Trade (DFAT) has been contacted for comment.