Hundreds of supporters of the Hamas attack have taken to the streets, angered by landmarks being illuminated in Israeli colours after the hardship the Palestinian people had suffered. 

An Israeli flag was burned at the Sydney Opera House while hundreds more protesters gathered in a Melbourne synagogue to mourn the dead and pray for the captured.

About 900 people are dead and thousands more wounded after the Islamist group Hamas attacked Israeli towns on Saturday in a continuation of a 75-year-long Arab-Israel conflict.

At least a further 400 were killed in Israel’s retaliatory attacks.

Hamas militants have taken multiple Israelis hostage, with Reuters reporting on Tuesday the movement, which controls Gaza in the Palestine territories, plans to execute captives if civilian houses are bombed.

There are unconfirmed reports of an Australian hostage. Defence Minister Richard Marles would not provide more detail. 

But he confirmed no Australian casualties at this stage.

“We will be pretty reticent about talking about any individual cases,” he told Seven’s Sunrise program on Tuesday.

He said nothing justified the “act of terror” and killing of innocents after hundreds of pro-Palestine protesters chanted anti-Israeli and anti-Jewish rhetoric.

Foreign Minister Penny Wong urged restraint to ensure the protection of civilians.

“Australia should always in any conflict be saying we want civilian lives to be protected,” she told ABC radio.

Australia Palestine Advocacy Network president Nasser Mashni said he couldn’t condone violence but questioned why Palestinian voices were only heard when Israel was attacked when 250 of his people were killed this year.

“No building has been ever lit up in the Palestinian flag,” he told ABC TV.

“Israel has been at war with Palestinians for 75 years, all we want is what everybody else wants – we want to go to music festivals, we want our children to go to school and come home safely, we want to live freely.”

Speaking earlier at a rally of about 500 Palestine supporters at Sydney Town Hall, Palestinian and academic Fahad Ali called on the words of South African apartheid activist Nelson Mandela, saying Palestine had been left with no choice but armed struggle. 

“The world has done nothing to support us,” he said.

“We did so not because we desired such a course but solely because the government had left us with no other choice.”

In Melbourne, hundreds of people including former federal treasurer Josh Frydenburg, gathered at Caulfield Shule for a vigil on Monday night.

Federal frontbencher Bill Shorten on Tuesday criticised the Sydney rally and the march, saying “some of the anti-Israel rhetoric has always been a mark of anti-Semitism”.

He pointed to anti-Jewish slogans being chanted at the gatherings “which is just disgusting”.

“It is un-Australian to attack someone because of what god they worship and … let’s call it what it is – it is anti-Semitism,” he told Nine’s Today show.

On Monday Prime Minister Anthony Albanese called for the pro-Palestine rally to be called off out of respect for the loss of life.

“I support people’s right to demonstrate their views. We’re a democratic nation … But what is to be served apart from creating a climate that is not conducive to peace?” he told Sydney radio 2GB.

Declaring himself a supporter of the two-state solution, Mr Albanese said Hamas’ attack was not in the interests of Palestinians.

“There’s no doubt there has been and continues to be Palestinian suffering but the actions of Hamas in this are completely indefensible,” he said.

Opposition Leader Peter Dutton also defended Israel.

“People who try to draw a parallel or argue equivalence between Israeli activity in their retaliation for the strikes and the barbaric attacks that we’ve seen by Hamas –  there is no comparison,” he told Sky News.

By Dominic Giannini and Kat Wong in Canberra