SYDNEY - Tens of thousands of Australians marched across Sydney's iconic Harbor Bridge on Sunday to protest the ongoing war and famine in Gaza.

The protest, organized by advocacy network the Palestine Action Group, went ahead on Sunday afternoon despite heavy rainfall.

Thousands of protesters carrying Palestinian flags walked north across the iconic bridge before being stopped by police due to safety concerns.

Organizers had expected around 50,000 people to attend the march, but police said on Sunday that it was difficult to estimate the crowd size.

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Addressing protesters at the start of the rally, Craig Foster, a former captain of the men's national football team, the Socceroos, called for Australia to withdraw all military and support to Israel.

"The starving children of Gaza cannot wait another day. End the violence, release all hostages and the thousands of Palestinian detainees held without charge," he said.

A simultaneous protest in Melbourne also attracted thousands of pro-Palestine demonstrators.