CAIRO – Galvanised by the biggest day of protest since their campaign to oust Hosni Mubarak's regime began, Egyptian pro-democracy campaigners attempted to blockade parliament Wednesday.

As speakers blared "Do not be tired. Do not be tired. Freedom isn't free," thousands of protesters remained camped under plastic sheets and the tracks of tanks, clinging to their "liberated" enclave on Cairo's Tahrir Square.

Around a thousand marched on parliament to demand its member's resignation. The protest was peaceful, and government troops secured the building, but the marchers swore they would not leave until the body was dissolved.

The night before they had been joined by several hundred thousand supporters for the biggest night of rallies yet in the two-week-old drive to topple their autocratic president and replace his 30-year-old regime.

"There can be no negotiation until he leaves. After he leaves we can talk about all sorts of things," said Essam Magdi, a 35-year-old lawyer, who has slept under an army tank since January 28 to prevent it from moving.

Egypt's 82-year-old president has deputised his vice president and former intelligence chief Omar Suleiman to draw selected opposition groups into negotiations on democratic reform before elections in September.

Some parties have joined the talks, but the crowds in Tahrir insist that Mubarak must go before they will halt the protest. Suleiman, however, warns that the transition must be slow and orderly if there is not to be chaos.

"A clear road map has been put in place with a set timetable to realise a peaceful and organised transfer of power," he said Tuesday on state television.

Afterwards, however, he told Egyptian editors that he would not allow "uncalculated and hasty steps" and warned "there will be no ending of the regime, nor a coup, because that means chaos."

The United States is watching events in the biggest country in the Arab world with great concern, hoping the transition to elected rule can take place without a descent into violence or an Islamist or military takeover.

On Tuesday, US 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 US calls for Egypt to immediately rescind an emergency law, which was renewed for two years last May and which Washington says gives the government sweeping powers to restrict basic freedoms.

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.

The presence of the Brotherhood at the protests has caused some in Western capitals to fear the movement might be hijacked by Islamists, but the demonstrators insist their goal is free elections open to all.

"We didn't want a military state or a religious state. We want a state of institutions and elections," said 34-year-old Atif Awad, a carpenter and a member of the Muslim Brotherhood.

The demonstrators plan to hold the square until Mubarak falls, and have been joined daily by supporters bringing food and staging street rallies. Tuesday's were the biggest yet, packing the area in defiance of a nightly curfew.

An Iraqi Al-Qaeda front group, the so-called Islamic State of Iraq, urged the Egyptian protesters to turn their backs on the "ignorant deceiving ways" of secularism, democracy and "rotten pagan nationalism."

Instead, it argued, they should launch a jihad for an Islamic state -- an idea that has long been rejected out of hand by the opposition movement, a motley coalition of leftists, secularists, Islamists and liberals.

The groups in the square have been inspired and mobilised by young Egyptian cyberactivists like Google executive Wael Ghonim, who promoted protest on his Facebook page and was held for 12 days blindfolded by authorities.

Freed on Monday, he was given a hero's welcome in the square at Tuesday night's protest, and he and others insist the revolt is a popular uprising.

"We are all Egyptians, Christian and Muslim, anybody who says differently is trying to divide us, make us scared of one another. That's the regime's idea," said Abdelrahman Sami, a 24-year-old doctor.

On Tuesday, Russia called for the UN Security Council to launch a mission to the Middle East to unblock the peace process between Israel and the Palestinians and to assess the turmoil in Egypt and other countries.

The Security Council has not visited the troubled region for more than three decades. Russia's UN ambassador Vitaly Churkin said council envoys should go to Israel, the Palestinian territories, Syria, Egypt and Lebanon.

Mubarak met Wednesday in Cairo with Russia's Middle East envoy Alexander Sultanov, but no details of the discussions emerged.