Activists plan a day of civil disobedience in Egypt on Saturday to mark the first anniversary since they toppled Hosni Mubarak but left an increasingly unpopular but defiant military in charge.
The call for strikes in universities and workplaces comes after a series of protests pressuring the military to transfer power immediately to civilians, rather than wait for planned presidential elections later this year.
The military, headed by Mubarak's long-time defence minister Field Marshal Hussein Tantawi, has said it will deploy additional troops across the country in response to the calls for a day of disobedience.
On Friday, thousands of protesters snaked through Cairo's streets to bypass military cordons and reach the defence ministry, chanting "Down with military rule!"
In a statement read out on state television late on Friday, the Supreme Council of the Armed Forces (SCAF) said it would not bow to threats or plots against the state.
"We will never yield to threats, and we will never give in to pressure," the SCAF said.
"We tell you quite frankly that our dear Egypt faces plans aimed at striking at the heart of our revolution.
"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."
The military, which has brutally quashed several protests in the past year, has played off the abundant suspicion in Egypt of foreign conspiracies.
Students in several universities have called for strikes for Saturday, with secular youth groups which spearheaded the revolt against Mubarak also taking part.
Tareq al-Khouly, an organiser of the April 6 youth group, said the plan was for a one-day strike which could be extended.
In a joint statement on Friday, the groups urged Egyptians "to support these strikes in order to end the unjust rule and build a nation in which justice, freedom and dignity prevail."
The call for strikes and protests has divided the country's political forces, with the Muslim Brotherhood -- the big winner in recent parliamentary elections -- coming out against it.
Many Egyptians complain that the economy has been battered by the lack of security and deadly violence in the wake of the 18-day revolt that forced Mubarak to resign on February 11 last year.
Protests against the military, idolised immediately after the revolt for not siding with Mubarak, have heightened fears among many that the Arab world's most populous nation could veer towards chaos, as the military itself warns.
On Friday the SCAF said the nation was at "the most dangerous turning point on our road to liberty, democracy and social justice."
Young activists who spearheaded the revolt against Mubarak believe the generals will try to exercise power through a pliant civilian government after presidential elections later this year.
The activists say the military should hand power to parliament, elected over three rounds in November and December, or to a civilian council ahead of presidential elections set to take place before the end of June.
The SCAF statement said it was determined to transfer power to an elected civilian body.
"We have kept the first promise and returned legislative power to the people's assembly," it said, adding that the parliamentary election took place in an atmosphere of "liberty and integrity."
"Presidential power will pass to the president of the republic after the election ending the period of transition, and your faithful army will revert to its original role," the military statement said.