JERUSALEM (AP) -- As Israeli-Hamas violence flared, President Barack Obama's new Mideast envoy promised on Wednesday a vigorous push for peace, saying Gaza militants must end their weapons smuggling and the blockaded borders must be pried open if a cease-fire is to take hold.
George Mitchell held his first round of talks with regional leaders to determine the next steps the Obama administration would take toward reviving peace negotiations following Israel's blistering military offensive against Gaza's Islamic Hamas rulers.
But continued violence in Gaza underscored the more immediate priority - shoring up the 10-day-old cease-fire.
Hours before Mitchell arrived in Jerusalem, Israeli warplanes pounded Gaza smuggling tunnels in reprisal for a Palestinian bombing on Tuesday that killed an Israeli soldier. After he spoke, militants fired a rocket into Israel and the military responded with another airstrike. There was no immediate word of any casualties.
After talks in Jerusalem with Israeli Prime Minister Ehud Olmert, Mitchell said consolidating the cease-fire was "of critical importance."
He said a longer-term truce should be based on "an end to smuggling and reopening of the crossings" into Gaza. Israel and Egypt have kept their borders with Gaza largely closed since the Islamic militant Hamas seized control of the territory in 2007.
Mitchell embarked on his Mideast foray just a week after Obama took office. After finishing his consultations in the region and with European leaders, he said he would report his recommendations to the president and Secretary of State Hillary Rodham Clinton.
But the envoy was silent on details of his meetings, and he has no news conferences planned during his 7-day tour, suggesting he would say little publicly before returning to Washington.
"The United States is committed to vigorously pursuing lasting peace and stability in the region," said Mitchell, who launched his diplomacy earlier Wednesday with Egyptian President Hosni Mubarak in Cairo.
He was expected to hold talks with pro-Western Palestinian President Mahmoud Abbas in the West Bank on Thursday. Mitchell has no plans to meet with Hamas, which the U.S., Israel and European Union consider a terrorist group.
It would be hard for the cease-fire to hold unless arrangements are made to stop the flow of arms to Hamas and to end the blockade of the coastal territory, which has deepened the deprivation of the 1.4 million Gazans trapped inside.
Mitchell said crossings should be opened on the basis of a 2005 agreement brokered by the U.S. that put the main border - between Egypt and Gaza - under the management of Abbas' Palestinian Authority, with European monitors deployed to prevent smuggling.
Hamas, which routed Abbas loyalists when it took over Gaza, has said it also wants a role at the crossings in recognition of its power in Gaza. Israel and Abbas do not want Hamas there.
Olmert told Mitchell that Hamas' power in Gaza "must diminish" and Abbas must "gain a foothold" there, an Olmert aide said on condition of anonymity because the meeting was closed.
Olmert said crossings between Israel and Gaza "will only open permanently" after the freeing of Sgt. Gilad Schalit, an Israeli soldier Gaza militants captured in 2006, the aide said. Israel has been trying to negotiate a prisoner swap with Hamas to secure Schalit's release.
"We reject these Israeli conditions. We will not accept them," Mashaal said.
Hamas wants Israel to free hundreds of Palestinian prisoners in exchange for Schalit.
Egypt has been exploring the possibility of including some Hamas figures in a Palestinian Authority presence at the border, but that would require some form of reconciliation between the factions. Egypt hopes to hold reconciliation talks between Hamas and Abbas by February.
One proposal is for a new unity Palestinian government including Hamas that could move forward with peace talks with Israel. But a 2007 try at a unity government dissolved in Palestinian infighting.
What's more, Israel, the United States and Europe demand Hamas drop its calls for Israel's destruction and renounce anti-Israeli attacks, something Hamas has refused to do despite years of bruising international sanctions and the recent war.
"It's for Hamas to change," European Union foreign policy chief Javier Solana said. "Offers have been made to Hamas to change and adapt."
The latest burst of violence was the worst since Israel and Hamas separately declared cease-fires on Jan. 18.
It started Tuesday when a remote-controlled roadside bomb on the Gaza side of the border with Israel killed one Israeli soldier and wounded three.
Israel swiftly sent tanks and bulldozers into northern Gaza to plow up the attack site and launched an airstrike that wounded a Hamas militant. Pre-dawn airstrikes Wednesday pounded tunnels used to smuggle arms, money, goods and people into Gaza from Egypt.
Defense Minister Ehud Barak canceled a planned trip to Washington this week to deal with the crisis, defense officials said.
Late Wednesday, a rocket fired from Gaza struck an open area in southern Israel, causing no injuries or damage, the Israeli military said. It was the first rocket launched since the cease-fire took hold, the military said. On Jan. 20, Israel's air force struck a Gaza mortar squad after it fired 12 mortars at Israel.
"Israel wants the quiet in the south to continue but yesterday's attack is a deliberate provocation designed to undermine and torpedo the calm," government spokesman Mark Regev told The Associated Press. "If Hamas acts to undermine the cease-fire, it will have no one but itself to blame for the consequences."
The Israeli offensive killed nearly 1,300 Palestinians, including hundreds of civilians, and caused an estimated $2 billion in damage, Palestinian officials say. The assault was launched to halt years of Hamas rocket fire on southern Israel.
Aid groups have complained that not enough supply trucks are getting through crossings Israel controls. Solana said Israel had promised him to increase humanitarian aid.
Israel has said an average of around 150 trucks a day are entering Gaza but Solana said he hoped that would jump to 400.