Concrete barricades have been installed to block vehicle access to Sydney's Martin Place following attacks in England and France in which terrorists deliberately drove into crowds of people.
The barricades in Martin Place, between Phillip and Elizabeth Streets, are part of an ongoing review of security in public spaces, the City of Sydney said in a statement.
"The City of Sydney takes advice from NSW Police and state emergency services on issues of public safety, including the installation of bollards and barricades to block vehicle access in response to security concerns," a spokeswoman said.
A NSW Police spokesman said the installation was not in response to any specific threat.
IS and Al Qaeda have encouraged followers to use trucks and cars as deadly weapons.

Concrete barricades have been installed to block vehicle access to Sydney’s Martin Place. (Channel 7) Source: Seven Network
A truck-ramming attack, claimed by IS, left 86 people dead and injured hundreds in the French city of Nice in 2016.
IS-influenced terrorists this month ploughed into pedestrians on London Bridge before stabbing passersby.
The Martin Place barricades are a temporary measure while the City considers more permanent features, such as bollards, garden beds or other landscaping features.
“Barricades or bollards will be rolled out to other stages in Martin Place over the coming weeks after further consultation with NSW Police and emergency services,” the City of Sydney spokeswoman said.
NSW Police said the advice followed a significant amount of work around vehicle mitigation strategies.
Similar security measures were introduced in Melbourne earlier this month after a car drove down Bourke Street Mall in January, killing six people and injuring more than 30.

The Martin Place barricades are a temporary measure while the City considers more permanent features. (Channel 7) Source: Seven Network
The incident was not terrorism related.
Temporary bollards have been installed in Federation Square, Bourke Street Mall and other busy public places.
Victorian Premier Daniel Andrew said the bollards would help prevent the threat of hostile vehicle attacks.