London attack: Second Australian confirmed dead

A second Australian has been confirmed dead following Saturday's terror attacks in London, the foreign minister said in a statement.

"The Australian Government is deeply saddened to confirm that two Australians have been killed in the London terrorist attack," Foreign Minister Julie Bishop said in a statement released Wednesday morning.

"We continue to work with the United Kingdom authorities who have asked that we await official confirmation of the identities of the victims, and for the families to be official notified, before we release their names."

Ms Bishop said in the statement the Australian government was continuing to work with the victims' families and requested their privacy be respected.

People observing a minute's silence in St Ann's Square, Manchester, in honour of the London Bridge terror attack victims. Photo: AAP

The victims' names have not been officially released, although the family of one - nurse Kirsty Boden, 28, from South Australia - has confirmed her death.

Ms Boden was killed when she rushed to the aid of other victims, her family said in a statement released on Tuesday night.

"Helping people was what she loved to do in her job as a nurse and in her daily life," the Boden family said in the release made through London's Metropolitan Police.

"As she ran towards danger, in an effort to help people on the bridge, Kirsty sadly lost her life."

A photo released by the family of Kirsty Boden.

Australian authorities are working with UK police to determine what happened to Brisbane woman Sara Zelenak, still missing after being separated from friends on London Bridge during the attack.

A Facebook post by a family friend shared hundreds of times on Monday appealed for information about the 21-year-old, saying she usually rang her mother daily.

Her family are reported to be distraught and "bracing for the worst".

It remains unclear if Ms Boden was hurt when three men used a van to run down pedestrians on the bridge or when they went on a stabbing rampage in a nearby market.

The three terrorists were quickly shot dead by police.

There are fears for Queensland woman Sara Zelenak who has not been heard from since the London terror attacks. Source: Facebook

"Kirsty was loved and adored by her family, friends and boyfriend," the family statement read.

"She was the most outgoing, kind and generous person who loved to help people. Helping people was what she loved to do in her job as a nurse and in her daily life."

The family, from Loxton in SA's Riverland region, asked for "the privacy we need to grieve away from the public eye".

Ms Boden worked in the theatre recovery ward at Guy's and St Thomas' Hospital which said she was a "one in a million" nurse who "always went the extra mile for the patients in her care".

SA Premier Jay Weatherill offered his condolences saying "Kirsty's death brings the horror of terrorism closer to home for all of us".

"It's the random nature of this heinous crime which makes it so hard to fathom," he said in a statement.