Prime Minister Scott Morrison has described the knife attacks in London and the Hague as "despicable acts" but is "not aware" that Australians have been caught up in the stabbings.
"Just terrible news out of London and The Hague," Mr Morrison said in a post on Facebook on Saturday.
"Whether it has been the despicable acts of terrorists in the UK, or as yet not determined in the Netherlands, Australians' deepest sympathies are with the victims and their families - they were innocent people going about their lives."
He said he was not aware of any Australians being caught up in the attacks at this stage, but is in close contact with local authorities.
London police are treating the attack on London Bridge on Friday, where a man wearing a fake explosive vest stabbed several people, killing two, as a terrorist attacker.
The attacker was fatally shot dead by police.
Labor frontbencher Kristina Keneally also offered her condolences, saying it was a "terrible tragedy".
"I would also like to acknowledge the bravery and the selflessness of the police, as well as members of the public, who acted with courage to ensure that this attack was not more serious than it already is," she reporters in Sydney.
Senator Keneally, Labor's home affairs spokeswoman, said it was a "tragic and timely reminder" of the collective threats facing Australians coming into the holiday season and that people needed to be alert to what is going on around them.
In the Netherlands, three people were stabbed in The Hague's main shopping district.
Police are searching for a least one suspect.
Dutch police say it is too early to say whether a terror motive was to blame for the attack.
