Intense diplomatic efforts between the US, EU and Arab countries to reach agreement on an international response to the crisis in Gaza appeared to be deadlocked last night, with no sign of unanimity over the appropriate way forward.

Despite the urgency of events on the ground, with the death toll approaching 700 in 12 days of fighting, dozens of Israeli tanks reported to be on the move in the Gaza Strip and air strikes continuing, the international community was unable to break the stalemate.

Two separate proposals were on the table at the UN in New York last night, with neither able to garner the necessary support. The first, a draft UN resolution proposed by Libya, demanded an immediate, permanent ceasefire in the Gaza Strip and expressed "grave concern at the crisis faced by the Palestinian people". It has widespread backing from Arab nations, but would certainly be vetoed by the US as Israel's leading ally.

The second proposal was a draft UN statement largely written by the UK, with US and French cooperation, also expressing "grave concern at the deepening humanitarian crisis in Gaza" and calling for both the Palestinian and Israeli civilian populations to be protected.

The second document has US backing, but has been opposed by a minority of Arab countries, who see it as a weak compromise and who want to hold out for a full UN security council resolution.

The failure to reach agreement is becoming increasingly embarrassing for the UN, which needs to be able to show resolute and unanimous action if it is to have any real influence on the conflict.

Efforts are likely to be redoubled today, with the US secretary of state, Condoleezza Rice, the foreign secretary, David Miliband, and other diplomats remaining in New York in the hope of breaking the stalemate.

Egypt's foreign minister, Ahmed Abul Gheit, revealed that a high-level Israeli delegation would arrive in Cairo today for technical discussions on the details of a possible ceasefire plan. Earlier speculation that talks would ensue between Israel and Hamas in Cairo were discounted.

Israel and Hamas yesterday both "welcomed" - but neither accepted - an earlier Egyptian-French initiative to end the fighting in the Gaza Strip. For the first time the US urged Israel to say yes to the ceasefire call, with Rice pressing the Israeli foreign minister, Tzipi Livni, by phone.

US attention seemed to boost the chances of progress. "Our goal must be the stabilisation and normalisation of life in Gaza," said Rice. But any ceasefire "has to be a solution that does not allow the rearmament of Hamas".

Barack Obama, the president-elect, broke his silence on the Gaza fighting to pledge that he would "engage immediately" with the Middle East when he takes office on 20 January.

Earlier, Nicolas Sarkozy, the French president, was forced to retract a claim that Israel and the Palestinians were both ready to sign up to the initiative.

Israeli officials said that Egypt's president, Hosni Mubarak, was seeking an initial 48-hour ceasefire, during which the finishing touches would be put to the plan. Israel said it accepted the "principles" of the plan but opposed a preliminary truce and wanted all the details of an agreement completed first.

Khaled Meshaal, the Islamist movement's Damascus-based political leader, told a Russian envoy that Hamas rejected "capitulatory" conditions. Ahmed Yusuf, a Hamas spokesman in Gaza, said in an article for the Guardian's Comment is Free website: "Hamas welcomes the Egyptian-French initiative. We recognise that it contains many positive elements but also elements that need more careful consideration."

For the moment the only Israeli concession has been to allow the delivery of aid for Palestinians - beginning yesterday - with a three-hour halt to bombing. Fighting resumed soon afterwards.

Agreeing humanitarian access and a truce is the first stage. But the second and far more complex element of any deal will be agreement to police Gaza's southern border to prevent Hamas smuggling in weapons once the fighting is over.

Diplomats following the negotiating process warned last night that the first part cannot work without the second for any length of time because a truce and humanitarian access do not address any of the fundamental concerns that led Israel to launch its Operation Cast Lead offensive on 27 December. Israel insists the key to ending the crisis is permanent measures to monitor and destroy tunnels under the Egypt-Gaza border.

Elements of the Egyptian-French plan and the continuing discussions at the UN in New York include calls for an international presence on the Egyptian side of the border, the so-called "Philadelphi corridor".

Various sources have reported that there would also be a naval presence to patrol the Gaza shoreline, perhaps commanded by the French. A small naval force was part of the arrangements for a ceasefire in Lebanon at the end of the 2006 conflict between Israel and Hezbollah.

Western officials say any border security arrangement would require US technical aid to Egypt as well as changes to the Israeli-Egyptian peace treaty of 1979 to change military dispositions in Sinai.

Crucially, missing from the plan so far is an agreed mechanism for Israel to lift the Gaza blockade, Hamas's principal demand, though it does mention reopening border crossings. Diplomats said there was hard bargaining over whether the UN statement should use the phrase "full and permanent" with respect to the crossings.

Peace plan proposals

• Forty-eight-hour ceasefire to allow humanitarian aid into Gaza. Israel is opposed to this.

• International presence on Egyptian side of border. This could include US combat engineers, Turkish troops and EU technical assistance. Possibly naval presence to patrol Gaza shoreline, perhaps commanded by the French.

• US technical aid to Egypt as well as changes to Israeli-Egyptian peace treaty of 1979 to alter military dispositions in Sinai.

• Missing from any plan so far is any agreed mechanism for Israel to lift the blockade of Gaza, Hamas's key demand.