Thousands of Mubarak supporters arrived at the square on horses and camels and launched attacks on protestors. The army had sent tanks and a helicopter to the square in anticipation of turmoil, but reports said they did not intervene.
Protesters claimed journalists were snatched from the crowd by masked police, who they say also seized cameras.
The Egyptian opposition has dismissed a vow by Mubarak to step down when his term of office ends in September, saying they want his immediate resignation.
The army had urged protesters to quit their rallies and “restore calm, security and stability” in the country as soon as possible.
The Egyptian Foreign Ministry has meanwhile rejected calls from the West for Mubarak to begin a transfer of power in the country.
“Egypt rejects what foreign countries propose. These countries assume the right to speak in the name of the Egyptian people and to voice demands of certain forces. The government of Egypt and its people view this as unacceptable,” Hossam Zaki, a spokesman for the ministry, said.
The United States, France, Britain, Turkey as well as the European Union called on Mubarak on Wednesday to begin the process of transferring power in the country.
Anti-government protests, which saw hundreds of thousands of demonstrators demanding President Mubarak’s resignation, broke out in Egypt last week.