CAIRO – Thousands of protesters flooded Cairo's Tahrir Square on Tuesday, galvanised by the release of a pro-democracy cyber activist as a revolt against Egyptian President Hosni Mubarak raged into a third week.

The embattled leader took a step earlier Tuesday towards democratic reform, authorising a committee to pursue constitutional change, a gesture that failed to appease the crowds who noisily demanded his immediate ouster.

"We are going in to support the people inside the square. They are the first line of defence," said 26-year-old Mahmud el-Naggar, who came from Fayyoum, south of the capital, with a group of friends and made for the square.

"We've heard there will be a million-strong demonstration today."

Protesters who arrived in the square, past a cordon of troops and tanks that searched them for weapons but made no attempt to halt the demonstration, were greeted by huge new posters of the "martyrs" of their revolt.

Many also carried the symbols of the Internet social networks Facebook and Twitter, which have become vital mobilising tools for the opposition thanks to online campaigners like Google executive Wael Ghonim.

Ghonim has himself become a hero to many in the movement, having started one of its most popular Facebook sites and been detained by the regime following a former day of protest on January 27.

Freed late on Monday, he gave an emotional interview to Egypt's Dream 2, weeping as he remembered those killed in two weeks of protests.

"I was blindfolded for 12 days, I couldn't hear anything, I didn't know what was happening," he said, in an appearance that has motivated the protests.

"I'm not a hero, I slept for 12 days," Ghonim said. "The heroes, they're the ones who were in the street, who took part in the demonstrations, sacrificed their lives, were beaten, arrested and exposed to danger."

For its part, the regime issued a decree forming a committee to oversee constitutional changes ahead of elections later this year.

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

"A clear road map has been put in place with a set timetable to realise a peaceful and organised transfer of power," he promised, in a televised address.

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.

Mubarak has promised not to stand for re-election in September, but opposition groups say any vote to replace the 82-year-old leader would not be fair under Egypt's current constitution.

As fresh crowds gathered, several thousand were already occupying the square -- the focal point of the past week's unprecedented protests -- sleeping under tents or rolled up in blankets at the foot of 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. "I never thought I'd sleep on asphalt with rain on my face and feel happy."

On Monday, Mubarak tried to buy time, pledging to raise public sector wages by 15 percent and ordering a probe into the recent deadly violence that has left at least 300 dead in the course of 15 days of protest.

"They announced a pay increase. They are trying to fool us. This is a political bribe to silence people," snorted 36-year-old demonstrator Mohammed Nizar as he queued patiently to join the crowds in Tahrir.

Mubarak met Emirati Foreign Minister Sheikh Abdullah bin Zayed al-Nahayan at the presidential palace in Cairo, his first high-level foreign visitor since he crisis began.

German magazine Der Spiegel reported preparations were under way for Mubarak to possibly visit Germany, where he underwent gall bladder surgery last March, for an "extended medical check-up." AFP was unable to confirm this.