PARIS - ISRAEL'S tank and troop assault on the Gaza Strip unleashed cries of alarm worldwide on Sunday, but Israel won heavyweight US backing and moves for an immediate ceasefire foundered at the United Nations.

The offensive was condemned across the Middle East, with Egypt saying the UN Security Council's silence on Israel's eight-day campaign of air strikes had effectively given Israel 'a green light' for the ground assault.

Asian nations expressed alarm, too, with Pakistan and China calling for an immediate end to the assault and Muslims in Indonesia urging war against the Jewish state.

But in New York, the Security Council failed to agree on a statement calling for a ceasefire after the United States argued that a return to the situation that existed before Israel's ground invasion was unacceptable.

US deputy ambassador Alejandro Wolff said after the four-hour sitting that Washington believed it was important that the region 'not return to the status quo' that had allowed Hamas militants to fire rockets into Israel.

'The efforts we are making internationally are designed to establish a sustainable, durable ceasefire that's respected by all,' Mr Wolff said. 'And that means no more rocket attacks. It means no more smuggling of arms.'

As thousands of Israeli soldiers and scores of tanks pushed into Gaza on Sunday, the British prime minister said assurances needed to be given to both the Israelis and Hamas to secure a ceasefire.

'I think everybody around the world is expressing grave concerns. What we've got to do almost immediately is to work harder than we've done for an immediate ceasefire,' Mr Brown said on BBC television.

'I can see the Gaza issues for the Palestinians - that they need humanitarian aid - but the Israelis must have some assurance that there are no rocket attacks coming into Israel,' he said.

'So first we need an immediate ceasefire, and that includes a stopping of the rockets into Israel.'

Russia dispatched President Dmitry Medvedev's special envoy for the Middle East, Alexander Saltanov, to the region, hoping it could help bring about a ceasefire.

'The new dangerous escalation in the armed conflict after the start of the Israeli land operation in Gaza is a matter of extreme concern,' the Russian foreign ministry said in a statement.

'It is essential, without delay, to put an end to the suffering of the civilian population on both sides, to stop the bloodshed and secure a mutual ceasefire.'

EU foreign policy chief Javier Solana said European nations stand ready to contribute international monitors to help keep the peace.

'The ceasefire has to be a ceasefire complied (with) by everybody and be clearly maintained,' Mr Solana told the BBC.

At least 23 Palestinians have been killed in Gaza since Israel's ground offensive began on Saturday, medics said Sunday.

In total, more than 485 Palestinians have died, including 80 children, with more than 2,500 wounded according to Gaza medics since Israeli military operations began on December 27.

Rocket fire from Gaza over the same period has killed four Israelis.

European reaction to the ground offensive revealed a sharp difference in tone from the official US line.

French Foreign Minister Bernard Kouchner said the decision to send troops into Gaza was a 'dangerous military escalation'.

The European Union's new Czech presidency said Israel's ground operation was more 'defensive than offensive", although it said Israel did not have the right to take military actions 'which largely affect civilians'.

Egyptian Foreign Minister Ahmed Abul Gheit said Israel's incursion into the impoverished territory was in 'brazen defiance' of international calls to end the offensive - and he blamed the Security Council for failing to act.

'The Security Council's silence and its failure to take a decision to stop Israel's aggression since it began was interpreted by Israel as a green light,' he said.

In Asia, Pakistani Foreign Minister Shah Mehmood Qureshi said the Israeli offensive was 'unjustified' and called for an immediate halt to the fighting.

Japanese Prime Minister Taro Aso warned that Israel's ground offensive would only aggravate difficulties for all concerned.

'I'm very worried that the dispatch of ground troops will make the situation much worse,' he said.

There was outrage in Africa as well.

Senegalese Pesident Abdoulaye Wade, who also holds the presidency of the Organisation of the Islamic Conference, called the Israeli ground offensive a 'flagrant violation of the most elementary principles of international law'. -- AFP