The human rights organization urged the military not to renege on its pledge to protect peaceful protesters and urged the government to refrain from violence.
"The army seems now to be reneging on its commitment to protect peaceful protesters," said Hassiba Hadj Sahraoui, deputy director of Amnesty International's Middle East and North Africa Program.
"The fact that such violence is allowed to continue as the army stands there begs the question of whether they have orders not to interfere."
The violence between protesters fits into a familiar pattern of political violence in Egypt, orchestrated by the authorities in order to disrupt and disperse protests.
"It looks like much of this violence is being orchestrated by the Egyptian authorities in order to force an end to the anti-government protests, restore their control and cling to power in the face of unprecedented public demands for them to go," said Sahraoui.
Earlier Wednesday, the army said anti-government protestors should return to their everyday lives, following the announcement on Tuesday by President Mubarak that he would not stand for re-election.
Later the army is reported to have allowed pro-Mubarak supporters to flood into Tahrir Square and attack the anti-government protesters.
An Amnesty International staff member trying to get to Tahrir Square was blocked by groups of pro-Mubarak demonstrators. He witnessed people leaving the square with injuries, apparently as a result of the clashes.
The attacks on anti-government demonstrators are now occurring in other key cities across Egypt. In Mahalla, an industrial area north of Cairo, eyewitnesses told Amnesty International researchers on the ground that they saw trucks carrying pro-Mubarak supporters leaving this morning.
In previous election years, Amnesty International has documented how hired thugs were used by the Egyptian authorities in order to intimidate voters and to disperse gatherings of their political opponents.
For more information, please visit: www.amnestyusa.org
SOURCE Amnesty International