Egyptian opposition groups has called for a million-man march on Friday as they fear the increasingly strong control of the Muslim Brotherhood over the country's politics.

The call for protests on Friday has spurred public debate especially after a Brotherhood cleric issued a religious edict, known as a fatwa, saying that killing anti-Islamist protesters was permissible.

Activists have demanded that President Mohammed Morsi take a strong stance against such statements.

Meanwhile, the Muslim Brotherhood has asked its young followers to come out on Friday to "protect" its offices from opposition protesters, escalating concerns of a possible showdown in Cairo.

Fathi El Sisy, head of the 24 August Union of the National Powers, one of the opposition groups calling for the march, refutes the claim that the protesters plan to attack the Brotherhood's headquarters.

"I do not know who is claiming that," he said. "If the Brotherhood's media organisation is the one doing that to put us in the hot seat, that's their problem."

Wafaa Saad, the general co-ordinator of the I am Egypt Campaign, said her group demanded that "the authorities protect the protesters, especially after some extremist clerics said these protesters [were] non-believers and that it [was] all right to kill them just because we [opposed] their opinion".

Bashir Abdel Fattah, a political analyst and editor-in-chief of Democracy magazine, said "those demanding to burn the headquarters of the Muslim Brotherhood are extremists and that could lead to a wave of violence".

A spokesman for Morsi said that the president supported the right to stage protests and that "it is unhealthy" to spread fears about protesters' safety.

Security authorities said in a statement that they would "confront with all firmness ... riots or chaos that harms citizens' interests".

Source: Agencies