Egypt has sent more than 1,000 extra troops to the border with the Gaza Strip, after Hamas and the Islamic Jihad movement warned that it could be breached if Israel's blockade of the territory continued.
The reinforcements were sent to the the Rafah border crossing and the Sinai coastal city of Al-Arish on Thursday.
Hundreds of thousands of Palestinians streamed across the border in January after Israel stopped deliveries off fuel, food and other basic necessities.
A security official said that lorries heading for the border were being stopped at the Suez Canal, in an a bid to remove the economic incentive for Palestinians to break out of Gaza and defeat Israel's lockdown of the territory.
"Hundreds of central security forces have arrived at their headquarters in El-Arish, northern Sinai, and are ready to be deployed in the border town of Rafah," the official said.
"Reinforcements have come from Cairo and the canal city of Ismailiya."
'Options open'
Khalil al-Hayya, a senior member of Hamas, on Wednesday said that all options were open to break the Israeli siege of the Palestinian territory.
"I expect that will happen next, and it will be greater than what happened before, not only against the Egyptian border, but against all the crossings," Hayya said.
The Egyptian foreign ministry criticised Hayya's statements as "unacceptable" and said any attempt to violate the sovereignty of Egypt would be dealt with seriously.
Weeks of Egyptian-mediated negotiations between Hamas and Israel, to re-open the Rafah crossing, failed to reach a deadlock after the two sides failed to agree on a truce arrangement.
Hamas asked for the blockade to be lifted and the truce to be extended to the West Bank, in return for halting rocket fire from Gaza.