Egyptian activists called for a second day of street action on Wednesday as authorities vowed to prevent further protests following huge anti-government rallies in which four people died.
The pro-democracy youth group April 6 Movement, the driving force behind Tuesday's protests -- the largest and most significant in Egypt since bread riots in 1977 -- urged people to head back to Cairo's main square Wednesday.
"Everyone needs to head down to Tahrir Square to take over the square once again," the group said on its Facebook page -- which along with Twitter had helped to organise Tuesday's protests.
In a separate statement, it urged Egyptians to carry on protesting.
"To continue what we started on January 25, we will take to the streets to demand the right to life, liberty, dignity and we call on everyone to take to the streets... and to keep going until the demands of the Egyptian people have been met," the group said.
But the interior ministry said further demonstrations were banned and anyone taking part would be prosecuted.
"No provocative moves, or protest gatherings, or marches or demonstrations will be allowed," the ministry said in a statement.
"Legal measures will be taken against anyone (in contravention), and they will be transferred to the prosecution," the statement continued.
Members of April 6 Movement said they would take to the streets regardless.
"We've started and we won't stop," one member told AFP on Wednesday.
Tuesday's demonstrations, dubbed "the day of anger" and inspired by the uprising in Tunisia, left three protesters and one policeman dead, according to medics who said one protester died Wednesday of his wounds.
Despite some 20,000 to 30,000 police being deployed in central Cairo, thousands of demonstrators marched to Tahrir Square on Tuesday, where they chanted in unison: "The people want the ouster of the regime."
They also tore down posters of Mubarak and chanted, "Mubarak get lost," "Bread, liberty, dignity," and "We will follow Tunisia."
Among demands are the departure of the interior minister, whose security forces have been accused of heavy-handedness; an end to a decades-old state of emergency; and a rise in minimum wages.
A statement released by the Egyptian interior ministry late Tuesday said security forces had decided to allow demonstrators "to voice their demands and exercise their freedom of expression," with a commitment to "securing and not confronting these gathering".
The ministry said a number of protesters, "particularly a large number of those affiliated with the Muslim Brotherhood... began to riot, damage public public property and throw stones at police forces."
The White House said on Tuesday that Egypt's government should be "responsive" to its people's aspirations.
"The Egyptian government has an important opportunity to be responsive to the aspirations of the Egyptian people, and pursue political, economic and social reforms that can improve their lives and help Egypt prosper," it said in a statement.
State Department spokesman Philip Crowley said that Washington was closely monitoring developments in Egypt.
"All parties should exercise restraint, and we call on the Egyptian authorities to handle these protests peacefully," Crowley said.
French Foreign Minister Michele Alliot-Marie said in Paris on Wednesday that France regrets the loss of life in the anti-government protests and supports calls for more democracy "in all countries."
"I can only deplore that there were deaths ... One must be able to demonstrate without there being violence, let alone deaths," the minister told France's RTL radio.