The military-affiliated Facebook page known as "the Administrator of the Supreme Council of the Armed Forces official page" issued a statement in the early hours of Wednesday – entitled 'The Final Hours' – in which it vowed to "sacrifice lives" to combat terrorists.

"The General Commander of the armed forces has said that it is more honourable for us [the army] to die than for the Egyptian people to feel threatened or terrorised," the statement read.

Egypt's military commander-in-chief and defence minister is General Abdel-Fattah El-Sisi.

"And we swear to God that we will sacrifice our blood for Egypt and its people against every terrorist, extremist or ignorant person," added the statement.

The declaration came only a few hours after a televised speech by President Mohamed Morsi, in which he defied opposition calls to step down and offered partial concessions to Egypt's political opposition.

Hours before Morsi's speech was aired, army spokesman Ahmed Ali refuted an earlier claim by the presidency that it would soon issue a statement in coordination with the military.

Tuesday marked the third day of mass protests in Egypt against President Morsi, which have been met with rival demonstrations by Islamists forces in support of the president's democratic legitimacy.

Notably, the army's 48-hour deadline to political forces to end the crisis – or face a military-imposed "roadmap" for Egypt's political future – will expire on Wednesday afternoon.

At least 17 people have been killed nationwide in political violence over the past week, raising fears of further street fighting in the event that the crisis escalates.