CAIRO (AFP) ― The United States urged Egypt to immediately lift an emergency law and launch democratic reforms as protestors staged the biggest show of defiance against President Hosni Mubarak in a three-week-old revolt.

But Mubarak’s newly appointed deputy, Vice President Omar Suleiman, warned that hasty reforms could spell “chaos” in the Arab world’s most populous nation.

In Cairo, hundreds of thousands flooded the now iconic Tahrir Square, hailing a charismatic cyberactivist and Google executive whose Facebook site helped kickstart the unprecedented protests Jan. 25.

Many carried banners praising the Internet social networks Facebook and Twitter, which have become vital mobilizing tools for the opposition, thanks to online campaigners like the Google executive, Wael Ghonim.

Ghonim, who was freed after being detained and blindfolded for 12 days, told an adoring crowd: “Egyptians deserve a better life. Today one of those dreams has actually come true, which is actually putting all of us together and as one hand believing in something.

“I’m not a hero, you are the heroes, you’re the ones who stayed on this square,” said Ghonim, who on Monday had tearfully described his ordeal at the hands of state security.

Earlier, the regime had issued a decree forming a committee to oversee constitutional changes ahead of elections due in September.

Mubarak, who has been in power for 30 years, says he will not stand for re-election and on Monday pledged to raise public-sector wages by 15 percent.

But many protestors, irate at mass unemployment, raging inflation and repression under Mubarak, are demanding the 82-year-old strongman’s immediate departure.

“The president welcomed the national consensus, confirming we are on the right path to getting out of the current crisis,” said Vice President Suleiman, whom many now see as the power behind the throne.

“A clear road map has been put in place with a set timetable to realize a peaceful and organized transfer of power,” he said in a televised address.

U.S. Vice President Joe Biden renewed an appeal for “immediate” and “irreversible” political change in a phone call to Suleiman, including a wider national dialogue with the opposition, a White House statement said.

He also renewed U.S. calls for Egypt to immediately rescind an emergency law, renewed for two years last May, which Washington says gives the government sweeping powers to restrict basic freedoms.

But Suleiman, speaking to local editors, warned against hasty reforms and said only dialogue and “a program of continuous steps” could lead to change.

“The second, alternative way, would be a coup ― and we want to avoid that ― meaning uncalculated and hasty steps that produce more irrationality,” he said, according to the official MENA news agency.

Suleiman said the government would continue talking with political factions and youth who spearheaded the protests, “affirming there will be no ending of the regime, nor a coup, because that means chaos,” MENA reported.

The former intelligence chief also warned against calls for “civil disobedience,” saying “the call is extremely dangerous for society, and we absolutely do not tolerate it.”

The vice president has begun meeting representatives of some opposition parties ― including the powerful Muslim Brotherhood, but not some of the street protest groups ― to draw up plans for a democratic transition.

But opposition groups say any vote to replace Mubarak would not be fair under Egypt’s current constitution.

U.N. chief Ban Ki-moon said the Egyptian people were frustrated and demanding “bold reforms” ― but pulled back from previous calls for an immediate transition by Mubarak.

While larger crowds gather daily to protest, several thousand occupy Tahrir Square day and night, sleeping under plastic sheets or army tanks.

“Patriotic songs about the country used to sound exaggerated, but we own the country now,” said 34-year-old doctor Issam Shebana, who came back from Sharjah in the United Arab Emirates to staff a makeshift clinic in the square.

“Yesterday, one man in his 60s said: ‘We were cowards. We kept quiet all these years, but you’ve done it.’ It’s inspiring. It’s a rebirth,” he said.