Efforts by foreign envoys to solve the crisis in Egypt have failed and the Muslim Brotherhood is responsible, the interim government has said.

The presidency announced that Wednesday marks the end of the first phase of diplomatic attempts to resolve the turmoil, which has been spiralling since July 3 when the military removed president Mohamed Morsi.

In a statement carried on state news agency MENA, it said: "Today ends the phase of diplomatic efforts, which began more than 10 days ago.

"The Egyptian state ... holds the Muslim Brotherhood fully responsible for the failure of those efforts [by foreign envoys] and what may be the consequences of this failure."

The prime minister warned, meanwhile, that the government's decision to clear the ongoing pro-Morsi protests is "final," and urged demonstrators to leave, saying they had "broken all the limits of peacefulness."

"The government's patience to bear this is nearly expired," he said, adding that any use of weapons against policemen or citizens would "be confronted with utmost force and decisiveness."

The remarks follow a call by Qatar's foreign minister, Khaled al-Attiya, to release members of the Muslim Brotherhood from jail, and come amid visits to Cairo by US senators John McCain and Lindsey Graham.

"This is essentially the first time we have heard from Egyptian officials on the outcome of mediation efforts," said Al Jazeera's Rawya Rageh, reporting from Cairo.

"There are so many concerns about possible security interference. The removal of sit-ins by force could result in a large number of fatalities should authorties decide to go down that route."

Foreign envoys from America, Europe, Africa and several Gulf Arab states have been visiting Egypt in the past month, with little success.

Thousands of pro-Morsi protesters have camped out in Cairo, demanding the resinstatement of the leader, and rejecting proposals by the interim leadership.

They say that several of their political leaders have been detained illegally, including Morsi himself.

The EU's foreign affairs head Catherine Ashton and an African Union delegate, former Malian president Alpha Oumar Konare, both managed to secure meetings with Morsi and reported he was in good health.

On August 1, the interim leadership first warned those protesting that it had authorised police to break up rallies in "gradual steps".