Egypt is to permanently open the Rafah border crossing to ease the Israeli blockade on Gaza, Nabil al-Arabi, the country's foreign minister, has said.
Arabi said Egypt would take "important steps to help ease the blockade on Gaza in the few days to come".
Speaking to Al Jazeera on Friday, the minister said Egypt would no longer accept that the Rafah border, Gaza's only crossing that bypasses Israel, remain blocked, describing the decision to seal it off as "shameful".
The announcement came days after Hamas, which controls Gaza, and their secular West Bank rivals Fatah, which controls the Palestinian Authority (PA), agreed to end their rift and form an interim government to prepare for elections.
In talks before the deal, the two sides had discussed reopening the crossing after positioning PA representatives at the border, a condition in a US-brokered 2005 border crossing agreement between Israel and the PA.
Mahmud Zahar, a senior Hamas official, told the AFP news agency that it was understood that the crossing, which under the 2005 agreement was to be monitored by European Union delegates, would be opened after a unity deal.
A senior official in Jerusalem said Israel was "very concerned" about the implications of the Rafah crossing being open.
Speaking on condition of anonymity, the official said Hamas had already built up a "dangerous military machine" in northern Sinai which could be further strengthened by opening Rafah.
"What power could they amass if Egypt was no longer acting to prevent that build-up?" the official said.
Earlier this week, unknown assailants in northern Sinai blew up a gas pipeline supplying Israel and Jordan, the second time it has been sabotaged in 10 weeks.
"We are troubled by the developments in Egypt, by the voices calling to annul the peace treaty, by the rapprochement between Egypt and Iran, and by the upgrading of relations between Egypt and Hamas," the Israeli source said.
"These developments potentially have strategic implications for Israel's national security."
Palestinian officials welcomed the Egyptian move, with Saeb Erakat, the PA's chief negotiator, saying it was one step towards loosening the siege on the Gaza Strip.
"We welcome this step by Egypt. We have been pressing them all the time to end the suffering of the people in Gaza, but the real siege is caused by Israel because there are many border crossing with Israel but only one with Egypt," he said.
"We ask Israel to open all the borders to end this crime against the Palestinian people in the Gaza Strip," he said.
Hatem Ewidah, the Hamas official in charge of border crossings in Gaza, also welcomed the move, but stressed it was "important to open the commercial crossing with Egypt" to reduce the impact of the blockade.
Shift in power
In a reminder of the border tensions, which is honeycombed with tunnels that supply Gaza with everything from cars and cattle to guns, police announced hours after Arabi's comments that smugglers had shot dead an Egyptian soldier on Thursday.
The border has remained largely shut since June 2006 when Israel imposed a tight blockade on Gaza after fighters snatched Israeli soldier Gilad Shalit, who is still being held.
The blockade was tightened a year later when Hamas seized control of the territory, ousting forces loyal to the Western-backed PA.
The UN has called the blockade illegal and repeatedly demanded it be lifted.