Central Security Forces conscripts at five police stations in northern Sinai have gone on strike to demand the release of Egyptian soldiers kidnapped in the region last week.
Dozens of conscripts stopped work on Monday in El-Hasna, Beir Abd, Nakhl, Sheikh Zowayid and Arish.
Seven Egyptian soldiers were kidnapped in the Sinai Peninsula on Thursday: a conscript of the armed forces and six police personnel.
The striking CSF conscripts warned they would join a protest at the Rafah border post if the kidnapped soldiers are not released.
Egyptian security forces continue to block the Rafah border post, which leads to the Gaza Strip, for the fourth day in protest at the kidnap.
The protest began on Friday when police strung barbed wire across the Rafah border post and chained up the gates.
Security forces at El-Ouga crossing, bordering Israel, began a strike on Sunday.
Egypt's army sent dozens of armoured vehicles and personnel carriers across the Suez Canal into North Sinai early on Monday, a security official told Al-Ahram Arabic news website on Monday.
The move comes as speculation grows that force could be used to rescue the kidnapped soldiers.
President Mohamed Morsi's office released a statement late on Sunday vowing to secure the release of the soldiers swiftly and safely and in a manner that would maintain the state's prestige.