CAIRO - Egypt put its security forces on the border with the Gaza Strip on high alert on Wednesday after Hamas threatened to repeat a January breach that saw hundreds of thousands of Palestinians flood across.
Security measures in the Sinai peninsula have been reinforced, especially in the area around the divided border town of Rafah, a security official said, as deadly clashes raged on the Gaza-Israel border.
Ambulances have also been sent to near Egypt's own 14-kilometer (nine-mile) border with the Gaza Strip.
Palestinian witnesses in the Gaza Strip said they saw increased numbers of Egyptian security forces deployed on the border, including snipers on Rafah rooftops and police with dogs patrolling the frontier.
Armored personnel carriers could also be seen on the Egyptian side, the witnesses said.
Egypt "will not take lightly the protection of its frontiers against any attempt to violate them, no matter who they are," the official MENA news agency quoted an official it did not identify as saying.
"Egypt's borders are a red line you cannot cross," the official said. "Egypt is capable of responding to any attempt to violate its frontiers."
On Tuesday, Khalil al-Hayya, a senior member of Hamas, the Islamist movement which controls the Gaza Strip, said that "all options are open to break the siege" by Israel.
"I expect that what will happen next will be greater than what happened before, not only against the Egyptian border, but against all the crossings," Hayya said.
'Move urgently and immediately to end siege'
The Egyptian foreign ministry issued a statement expressing "profound amazement" at the breach threats.
"These statements are unacceptable and in flagrant contradiction with efforts Egypt has made to lift the blockade on the Gaza Strip and reach a truce allowing Palestinians from Gaza to live a normal life," it said.
"Any attempt to violate the sovereignty of Egypt's frontiers by force or ... illegally will be dealt with seriously and with appropriate firmness," it said, adding that any breach would damage the Palestinian cause.
Israel has sealed off Gaza from all but vital goods since Hamas seized power last June, in a bid to halt rocket attacks from the territory and to put pressure on the Islamist-run government.
"We call parties to move urgently and immediately to end the siege and warn of an unprecedented explosion if it continues," Hayya said.
On Wednesday, gun battles raged on the Gaza-Israel border, leaving two Israelis and one Palestinian dead, Israeli emergency services said.
Hamas has been negotiating with Egypt for weeks in a bid to reopen the Rafah crossing, the only gateway to Gaza that bypasses Israel.
Palestinian president Mahmud Abbas has called for a return to a 2005 agreement in which European Union monitors were stationed at the crossing and Israel monitored it with electronic surveillance.
But Hamas, which seized control of Gaza after routing forces loyal to Abbas, has rejected any foreign involvement and demanded that Rafah be reopened as an Egyptian-Palestinian crossing.
On January 23, Palestinian militants demolished the border barricades between Gaza and Egypt, sending hundreds of thousands of Gazans streaming into Egypt to stock up on supplies.
Egyptian and Hamas forces resealed the frontier on February 4.