Efforts by Islamist figure Ahmed Kamal Abul-Magd to mediate between the Muslim Brotherhood movement of toppled president Mohamed Morsi and the country's  interim government appear to have reached an impasse.

The Islamist thinker and constitutional expert attempted to end the current political deadlock by proposing that Islamists acknowledge the interim "revolutionary authority" as a first step towards national dialogue, as tension simmers following the overthrow of the country's Islamist leader and an ensuing clampdown on his group.

His suggestion has been rebuffed by Islamists, who consider it tantamount to legitimising a "coup" against the country's first democratically elected president.

Abul-Magd's initiative was launched almost a week ago and targeted pro-Morsi group - the National Alliance to Support Legitimacy (NASL). It was initially welcomed by Islamists before they accused the mediator of prejudice towards the country's interim leaders.

In response to the proposal, Mohamed Ali Bishr, Muslim Brotherhood figure and leading member of the NASL, outlined a set of stipulations for potential dialogue , including the rejection of "foreign interference" and any political role played by the military, which deposed Morsi on 3 July amid mass popular protests against his rule.

Abul-Magd urged Islamists to cease their "media and stunt escalation," which he said would only incur confrontation with other Egyptian forces.

'Bias' and 'Manoeuvre'

Bishr slammed the "conditions" Abul-Magd proposed as "unacceptable" and "biased."

"Accepting such conditions would bias one side over another, and amount to recognition of the coup, which is totally unacceptable," Bishr, former local development minister under Morsi, said in a statement on the Brotherhood's Freedom and Justice Party website.

He also questioned Abul-Magd's reluctance to reveal the content of discussions without consent [from Islamists] on some "preconditions."

However, Bishr emphasised that his group welcomes initiatives for dialogue from any "impartial" party, conditional upon the return of what he termed "the constitutional legitimacy" of the suspended 2012 charter.

A day before Bishr's statement, mediator Abul-Magd said he would wait for a "formal" reply from the Brotherhood independent of any attempt to "manoeuvre" the situation.

During a visit to Cairo in early October, European Union foreign policy Chief Catherine Ashton called for dialogue and urged the Brotherhood and the interim administration to take part in an inclusive political process, but neither side appeared willing to heed the call.

Analysts have said that the Brotherhood would use street protests against the interim government as a bargaining chip to pressure for the release of prominent Islamist leaders detained by authorities following Morsi's deposition.

Egyptian authorities have carried out a sustained clampdown on the Islamist group and their allies since Morsi's ouster on 3 July. The majority of the group's mid- and upper-echelons have been rounded up, along with several thousands of other members and Islamist activists.

"I suppose the ball is no longer in my court, but rather in that of the National Alliance," the Islamist constitution specialist told independent daily Al-Shorouk on Sunday.

He noted that Islamists seemed to be suffering from "difficulties" and "internecine fissures," preventing them from "making wise decisions" regarding the country's political deadlock.

Interim authorities have imposed a transitional roadmap following Morsi's removal, which saw the 2012 constitution suspended and promised parliamentary elections and a presidential vote by early next year.

Egypt has plunged into cycles of political violence since Morsi's exit, with street fighting killing at least 1000 since.

In one of the bloodiest recent flare-ups, 57 people were killed on Sunday 6 October when Morsi loyalists clashed with opponents and security forces, on a day when thousands of pro-military protesters took to the streets to celebrate the anniversary of the 1973 Arab-Israeli war.