Egypt's ruling military said on the eve of the first anniversary of the revolt that toppled Hosni Mubarak that it will not bow to threats or plots against the state, official television reported.
"We will never yield to threats, and we will never give in to pressure," the much-criticised Supreme Council of the Armed Forces (SCAF) said in a statement broadcast by the channel.
Ahead of a planned day of disobedience by activists, the SCAF also said the country was the target of conspiracies aiming to sow instability.
"We tell you quite frankly that our dear Egypt faces plans aimed at striking at the heart of our revolution," the statement said.
"We are facing plots against the nation aiming to undermine the institutions of the Egyptian state, and to topple the state itself so that chaos reigns."
Activists were planning a day of strikes in universities and workplaces on Saturday to mark 12 months since they toppled Mubarak but left an increasingly unpopular military in charge.
The call for a day of action comes after a wave of protests pressuring the military to transfer power immediately to civilians, rather than wait for planned presidential elections later this year.