Egypt has arrested 15 Palestinians armed with weapons and explosives who are believed to have crossed the Gaza border since it was breached last week.
Egypt wants to restore shared control of the border with Gaza
The men, who were detained in the Sinai peninsula, also had detonators, flak jackets and grenades, officials said.
The arrests came as Egyptian government officials held talks with the Palestinian militant group, Hamas, on how to re-establish border controls.
A Hamas official said progress had been made, but no agreement was reached.
The group, which seized control of the Gaza Strip in June, is pressing for a role in how the border crossing is operated in the future.
Hamas has indicated that it could prevent Egypt from sealing the frontier if it is not officially recognised. A previous Egyptian attempt last Friday ended with militants bulldozing a second hole in the border.
Hundreds of thousands of Palestinians had been crossing freely into Egypt near the town of Rafah since 23 January to buy essential supplies made scarce by a recent tightened Israeli blockade.
The Israeli government imposed the restrictions a week earlier after a sharp rise in rocket attacks by militants based in Gaza.
Egyptian officials said suspected militants from Hamas and Islamic Jihad were among the 15 Palestinians arrested near the border town of al-Arish and in remote parts of Sinai in recent days.
All of those detained had entered Egypt via Rafah, apart from two who had travelled from Gulf Arab states, they added.
Police are reportedly looking for four other armed Palestinians who are believed to have crossed the border.
Israel has said it is concerned that militants are taking advantage of the freedom of movement to bolster their stores of weapons and explosives.
It has also warned that foreign militants might use the opportunity to infiltrate the coastal territory and launch attacks on Israel.
17 January: Israel seals border following rise in rocket attacks
20 January: Gaza's only power plant shuts down
22 January: Israel eases restrictions
22 January: Egyptian border guards disperse Palestinian protest against closure
23 January: Border wall breached
In order to limit such activity, Egyptian security forces have maintained a tight security cordon in place around the border area to keep Palestinians from travelling further into Egypt.
Barbed wire and cement has also been used to close sections of the border and Egyptian troops have been deployed along the breaches.
On Friday, the forces began preventing Palestinian vehicles crossing into Egypt, but are still allowing people to enter on foot. Heavily-laden Egyptian trucks are also being allowed to continue transporting supplies into Gaza.
A senior Egyptian security official told Reuters news agency on Thursday that there had still not been official word on when the borders would be closed completely.
He said any closure would be incremental to avoid friction with Palestinians.
The Egyptian government has held talks in Cairo with both Hamas, which controls Gaza, and the President of the Palestinian Authority Mahmoud Abbas.
Hamas official Sami Abu Zuhri told Reuters that Thursday's talks had "concentrated on the facilitation of movement and the entry of Palestinians on the Egyptian-Palestinian border".
Egypt has been holding talks with Palestinian leaders in Cairo
"It is still early to talk about details," he said.
Mr Abbas has rejected Hamas' claim over the border and reiterated his refusal to negotiate with Hamas leaders.
"Hamas has to end its coup in Gaza, accept all international obligations, and accept holding early elections," he told a press conference. "After that, our hearts are open for any dialogue."
But Hamas leader Mahmoud Zahhar said yesterday that discussion about shared control "contradicts reality".
"The reality is that there is a legitimate government. We will not give up our legitimacy to anybody," he said.
Nevertheless, Mr Zahhar said that while no agreement had been reached, some progress had been made.
Cairo wants to see a return to a 2005 agreement by which the border would be controlled by the Palestinian Authority and monitored by the EU and Israel.