Egypt's army sent dozens of armoured vehicles and personnel carriers across the Suez Canal into North Sinai early on Monday, a security official has told Al-Ahram Arabic news website.
The move comes as speculation grows that force could be used to rescue seven Egyptian soldiers kidnapped  last week.
Seven Egyptian security personnel, including one member of the armed forces, four port security officers, and two state security officers, have been held by unidentified kidnappers in the Sinai Peninsula since Thursday.
A security source said the kidnappers have demanded the release of Islamist militants detained for almost two years.
The militants, who allegedly belong to Tawhid wal-Jihad, were convicted of killing five security officers and one civilian during attacks in June/July 2011 on an Al-Arish city police station and a North Sinai branch of the Bank of Alexandria. Twenty-five individuals were charged in the case.
Early on Monday, unidentified gunmen stormed an Egyptian security base in the Sinai Peninsula and exchanged gunfire with forces inside the base before retreating, security sources told Reuters.
The gunmen attacked the base in the Al-Ahrash area in North Sinai from a truck and fired automatic weapons. The attack did not result in any casualties.