Mr Shorten said he has spoken with PM Tony Abbott and given him his “full support at this time”, reports The Guardian.
“Our thoughts and prayers today are with the innocent people involved in this morning’s incident in Martin Place, Sydney,” said Shorten.
“Our thoughts are also with their families who are seeing this incredibly distressing situation unfold, along with the rest of Australia.
“I have full confidence in the skill and professionalism of our police and security agencies.
“I have spoken to Prime Minister Tony Abbott this morning and offered him the Opposition’s full support at this time.
“Australians can be assured that we are one when it comes to keeping Australians safe.”
Tony Abbott is due to address the public shorty.