US Secretary of State Condoleezza Rice will travel to New York Tuesday to signal Washington is making "every possible diplomatic effort" for a durable ceasefire in Gaza, her spokesman said.
But spokesman Sean McCormack lowered expectations for a ceasefire resolution to emerge Tuesday from a UN Security Council meeting that the chief US diplomat will attend in addition to her talks with Arab and other allies.
Arab countries accuse Washington of blocking ceasefire efforts in order to give Israel more time to defeat Islamist Hamas radicals who have run the Gaza Strip since ousting the rival US-backed leadership of Mahmud Abbas in 2007.
Rice is due to hold bilateral talks with Abbas. He is Israel's negotiating partner in the peace talks that Rice helped revive in Annapolis, Maryland in November 2007 but which are now eclipsed by the Israeli offensive in Gaza.
State Department officials say she is also expected to meet her counterparts from Arab and European countries as well as Ali Babacan, the foreign minister of non-Arab Turkey, which has been pushing its own proposals for a ceasefire.
"Her going up there is a signal that we are making every possible diplomatic effort to try to bring about a ceasefire on the terms that we have outlined," McCormack told reporters at the daily news briefing in Washington.
But Arab and other countries are pressing for an "immediate" ceasefire without the same conditions Washington wants.
Washington wants "an immediate ceasefire that is durable, sustainable and not time-limited," McCormack said.
A ceasefire must tackle efforts to secure an end to rocket attacks on Israel, open international border crossings with Gaza and stop weapons to Hamas through tunnels along the border with Egypt, according to McCormack.
The United States is looking at a partially-implemented 2005 agreement as "a model" to open up the borders in a way that ensures trade with the Palestinians but guarantees security for Israel, he added.
Asked if the idea was aimed at bringing back the Abbas-led Palestinian Authority to the Gaza Strip, McCormack replied: "No, it's a side effect, perhaps, of having an agreement that is consistent with the 2005 agreement."
White House spokeswoman Dana Perino meanwhile stopped short of endorsing a proposed humanitarian truce for Gaza.
"We are working to help bring about a durable ceasefire," spokeswoman Dana Perino told AFP when asked if President George W. Bush would be ready to back a humanitarian truce.
She said that "humanitarian aid has been flowing to the region, provided by Israel and the UN."
The 11-day-old Israeli offensive on Hamas in the Gaza Strip has killed at least 635 Palestinians, Gaza medics said on Tuesday. Another 2,900 people have been wounded.
Perino spoke as France worked with Arab states on a draft UN resolution calling for an immediate end to the Israeli military offensive in Gaza as well as to rocket fire into Israel by Gaza-based militants.
The text would also urge the lifting of the Israeli siege of Gaza to allow humanitarian access to the beleaguered Palestinian population, protection of Palestinian civilians, a resumption of the Israeli-Palestinian peace process and a means to monitor the truce and protect civilians, diplomats said.
Perino struck a cautious tone over French President Nicolas Sarkozy's diplomatic effort to persuade Syria to push its ally Hamas to agree a truce.
McCormack played down chances for an immediate ceasefire as he said various proposals were "not all synched up at this point" and he stressed that Rice's bilateral talks were more significant than the Security Council meeting.
He appeared to suggest a ceasefire could be achieved outside the security council.
"I can't predict what form or format or what mechanism will be used to achieve that. I think ...we're open in that regard, but I wouldn't expect a resolution today, a Security Council resolution today," McCormack said.
