SYDNEY - Thousands of protesters from Australia to India rallied to voice their support for Palestinians on Sunday, as Israel mounted a ground assault in Gaza and the death toll from air strikes climbed.

In Sydney an estimated 3,000 people demonstrated outside the city's Town Hall to condemn the military offensive, shouting "Free, free Palestine; free, free Gaza" and holding signs declaring "Shame Israel Shame".

"Israel is targeting the civilians of Gaza with these bombings, and that is shameful and that is what we condemn," Greens party senator Lee Rhiannon told the crowd. As Israel's air campaign in the Gaza Strip entered its sixth day, the overall death toll rose to 165 with more than 1,000 injured and the UN Security Council called on both sides to declare a ceasefire.

In Indonesia, the world's most populous Muslim nation, about 500 people marched in the capital Jakarta shouting "Allahu Akbar" (God is the Greatest) and carrying Palestinian flags and posters of children killed in the offensive. "This is a show of solidarity for our Muslim brothers and sisters in Gaza who are being oppressed by Israeli occupiers. We Indonesian Muslims share their suffering and pain," activist Adityo Nugroho told AFP.

Israel began Operation Protective Edge before dawn on Tuesday in an attempt to halt cross-border rocket fire by militant groups.

In Hong Kong organisers of a pro-Palestinian rally said about 300 people, mostly from the city's Muslim community took part. Some held up banners depicting the Israeli flag with the star of David replaced by a swastika, as protesters marched through the streets in the sweltering heat.  "We came to support our sisters and brothers in Gaza and our request is that they stop the killing of innocent children women in men in Gaza," 21-year-old restaurant manager Kashi Anjum told AFP.

In the Indian capital New Delhi about 100 protesters, mainly students, gathered outside Israel's embassy carrying placards stating "We are with you Gaza" and "Say no to Zionist genocide". Protests were also held in Tokyo and Malaysia on Friday.

Meanwhile, Pope Francis on Sunday appealed for peace in Gaza during his weekly Angelus prayer, calling for "concrete gestures to build peace" as the deadly six-day offensive escalated. In an address to thousands of pilgrims on St Peter's Square Francis spoke of the "tragic events of the last few days". Francis visited the Middle East in May and held a joint prayer in the Vatican with Israeli President Shimon Peres and Palestinian president Mahmud Abbas in June. "I urge all interested parties and all in local and international political office not to spare in prayer and efforts to cease all hostilities," Francis said.

Referring to the June 8 joint prayer, he said: "Some people might think that such a meeting was in vain. But this is not the case because prayer helps us not to be conquered by evil or resign ourselves to violence and hatred." As world powers prepared to meet in Vienna over the escalating conflict, the Palestinian death toll from Israel's punishing air campaign hit 165 following the bloodiest day yet, which left 56 people dead.

Meanwhile, the foreign ministers of Germany and Italy were due in the Middle East this week amid an escalating conflict between Israel and Hamas in the Gaza Strip, officials said Sunday. "I can confirm that Foreign Minister (Frank-Walter) Steinmeier will travel in the Middle East tomorrow and the day after," a ministry spokeswoman told AFP as diplomatic efforts to halt the bloodshed intensified. She declined to provide further details.

Israeli media said Germany's top diplomat was expected to hold talks in Israel, the West Bank and Jordan.

Italian Foreign Minister Federica Mogherini, who holds the EU's rotating presidency and is seen as a possible candidate for European Union foreign policy chief, is also heading to the region, Rome said.

Her ministry said Mogherini would be in Israel and the Palestinian territories from Tuesday to Thursday and in Egypt, a traditional mediator in the Middle-East conflict, from Friday to Saturday. A summit on Wednesday is expected to decide on nominations to the EU's leadership following European Parliament elections.

German Chancellor Angela Merkel condemned rocket attacks on Israel from Gaza in a telephone call with Israeli Prime Minister Benjamin Netanyahu on Wednesday, saying their was "no justification" for such attacks.

Her spokesman Steffen Seibert told reporters Friday that the current escalation could only be calmed if Hamas stopped rocket attacks against Israeli cities.

"We underline Israel's right to defend itself against these attacks while maintaining proportionality," he said. "It is crucial that further escalation be prevented and deaths and injuries among civilians on both sides must be avoided."

Steinmeier was expected to discuss an international push for a ceasefire in Gaza with US Secretary of State John Kerry and his British and French counterparts in Vienna Sunday.

Israel stepped up its campaign in Gaza Sunday, warning Palestinians in the north to flee after marines mounted a ground attack.

The Palestinian death toll from a punishing six-day Israeli air campaign hit 166, following the bloodiest day yet in which 56 people were killed.