Egyptian authorities are warning the Islamist Muslim Brotherhood against staging violent protests.
The government said on October 5 it was tightening security in all cities and strategic installations, a day after clashes in Cairo killed at least four people.
Those clashes broke out when hundreds of supporters of ousted Islamist President Muhammad Morsi tried to converge on Cairo's Tahrir Square.
Earlier on October 4, at least two Egyptian soldiers were killed in an attack by suspected militants on an army convoy east of Cairo.
UN Secretary-General Ban Ki-moon has expressed concern over rising unrest in Egypt, and stressed "the importance of peace protest."
Based on reporting by AFP and Reuters