Pro-democracy activist and Nobel Laureate Mohammad ElBaradei, who defied house arrest to join the protesters at the Tahrir Square last night, asked the embattled president to "step down today itself."
"It is loud and clear from everybody in Egypt that Mubarak has to leave today," ElBaradei said in an interview aired on CNN.
"He needs to leave today... to be followed by a smooth transition (to) a national unity government to be followed by all the measures set in place for a free and fair election."
Meanwhile, the show of defiance continued as protesters assembled in central Cairo and called for a general strike today. They vowed to continue the protest until the fall of Mubarak`s regime, even as the death toll in the last six days of violence crossed 150.
"The army has to choose between Egypt and Mubarak," said a banner in Tahrir Square.
Egyptian judges and scholars from world`s prestigious Islamic seminary Al-Azhar joined mass protests, calling for an to Mubarak`s 30-year rule.
Meanwhile, US President Barack Obama has sought restraint and favoured "concrete steps" aimed at advancing political reforms in Egypt.
Secretary of State Hillary Clinton yesterday called for an "orderly transition" to democracy in Egypt, saying the legitimate grievances of the people will have to be addressed.
In a desperate move to cling to power, Mubarak, 82, yesterday visited the military headquarters and met the newly appointed Vice President Omar Suleiman and top commanders after which more troops and armoured vehicles moved on to the streets.
The Army increased its presence on the streets of the capital, and blocked roads with tanks and flew in fighter jets over the city after lootings and arson were witnessed.
However, the protests continued unabated and the military did not make any move to target or disperse thousands of protesters at the Tahrir Square, which has now become a symbol of the mass uprising, and a centre where demonstrators have been converging defying night curfews.
Many armymen had earlier doffed uniforms to join the uprising against Mubarak. All eyes are now on the powerful military which is widely believed to have a pivotal role to play in seeing a smooth transition of power.