CAIRO – Thousands more Egyptian demonstrators joined a mounting tide of protest against President Hosni Mubarak's regime on Thursday, despite stark threats of a government crackdown.

The revolt now holds two permanent protest camps in Cairo, blocking both the parliament building and the city's iconic Tahrir Square with noisy rallies staged under the watchful gaze of government troops.

Both sides have toughened their rhetoric, with Vice President Omar Suleiman tacitly threatening to turn to the military to regain control. In response, the protesters moved to blockade parliament and reinforce Tahrir.

"No to Suleiman. No to American agents. No to Israeli spies. Long live Egypt. Down with Hosni Mubarak," they chanted in the street outside parliament, now lined with makeshift shelters and anti-regime posters.

Soldiers were deployed to protect the building but, to the amazement of many activists more used to the strong-arm tactics of Mubarak's autocratic regime, they made no attempt to dislodge the growing protest.

"If we don't die here we'll die in prison, I'd prefer to die here," said Attiya Abuella, 24, an unemployed graduate who said he had been jailed last year for 60 days, often naked and in chains, for taking photographs.

The night before, Egyptian Foreign Minister Ahmed Abul Gheit warned that the army, until now a mostly neutral force, would intervene if the protests against Mubarak's 30-year-old US-backed rule escalated.

"If chaos occurs, the armed forces will intervene to control the country, a step ... which would lead to a very dangerous situation," he told Al-Arabiya television, according to a translation from the state news agency.

Abul Gheit also slammed the United States, accusing it of seeking to force its will on Egypt by demanding immediate reforms.

"When you speak about 'prompt', 'immediate', 'now', as if you are imposing on a great country like Egypt, a great friend that has always maintained the best of relationships with the United States, you are imposing your will."

Shortly after his comments, Washington renewed its calls on the Egyptian army to show restraint.

In Tahrir Square, volunteers have erected portable toilets, indicating the protesters have no intention of leaving the "liberated" area, now a sprawling tent city with sound stages, food vendors and a mobile phone charging station.

On Wednesday, unrest gripped the remote oasis of Kharga, where at least five people were killed and 100 wounded when security forces opened fire on demonstrators, a security official told AFP.

In the Suez Canal city of Port Said, some 3,000 protesters stormed a government building, torching office furniture and the governor's car. There were other protests across the country, and strikes at several firms.

Meanwhile, Wael Ghonim, a Google marketing executive and cyber-activist who has emerged as a prominent spokesman for the revolt, promised to stay out of politics once the dissidents' demands are met.

The 30-year-old was freed Monday after 12 days in custody, and was swiftly propelled to the forefront of the uprising, addressing adoring crowds.

"I promise every Egyptian that I will go back to my normal life & not be involved in any politics once Egyptians fulfil their dreams," he wrote on his Twitter account.

The 82-year-old Mubarak has charged Suleiman, his long-time intelligence chief, with drawing selected opposition groups into negotiations on democratic reform before elections due in September.

Some parties have joined the talks, but the crowds in Tahrir Square insist that Mubarak must go before they will halt their occupation.

The Muslim Brotherhood, the country's best organised opposition group despite a half century of illegality, has moved to reassure observers who fear an Islamist takeover should Mubarak's regime be toppled.

"The Muslim Brotherhood does not seek power. We do not want to participate at the moment," senior leader Mohammed Mursi told reporters, adding that the movement would not field a presidential candidate.

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