Egyptian reinforcements have been sent to the border area
Egypt has sent 1,200 extra security personnel to the border area with Gaza, officials say.
The Egyptians fear another breach of the frontier by Palestinians trying to break the Israeli blockade of Gaza.
A senior member of Hamas, which controls Gaza, threatened on Tuesday to repeat a breach of the border with Egypt earlier this year.
Hundreds of thousands of Palestinians poured into Egypt in January to stock up on goods in short supply.
An official said hundreds of security staff had arrived in northern Sinai, ready for deployment to the border town of Rafah.
Lorries carrying goods to the border have been stopped at the Suez Canal, the official said.
On Tuesday, Hamas politician Khalil al-Haya described the situation in Gaza as "no longer bearable" and renewed threats to breach the border.
"I say clearly all options are open... What is coming will be bigger than what happened in the past, not only at the borders with Egypt but in other areas too," he told a news conference.
The Egyptian Foreign Ministry said any attempt to violate Egyptian territory would be unacceptable, describing Mr al-Haya's statement as "unacceptable".
January's breach of the border came after Palestinian militants destroyed barricades. The frontier was closed again in early February.
Israel tightened its blockade of the Gaza Strip when Hamas seized control of Gaza in June.
It says the blockade is necessary to prevent rocket attacks by Palestinian militants on Israeli communities near the border.
Hamas has been negotiating with Egypt for the Rafah crossing point to be re-opened.