|Protests in Egypt are often quashed swiftly by the police, who prevent marches against the government [EPA]
The Egyptian government has warned activists hoping to emulate Tunisian pro-democracy protesters that they face arrest if they go ahead with mass demonstrations some have labelled as the "day of wrath".
Hundreds have protesters have begun to take to the streets in Cairo, chanting slogans against the police, the interior minister and the government.
They were gathering outside the Egyptian capital's largest courthouse on Tuesday and marching across the business district.
The rallies have been promoted online by groups saying they speak for young Egyptians frustrated by the kind of poverty and oppression which triggered the overthrow of Tunisia's president.
Black-clad riot police, backed by armoured vehicles and fire engines, have been deployed in a massive security operation in Cairo, with the biggest concentrations at likely flashpoints, including: the Cairo University campus, the central Tahrir Square and the courthouse where protesters are said to be gathering.
Coinciding with a national holiday in honour of the police, a key force in keeping president Hosni Mubarak in power for 30 years, the outcome in Egypt on Tuesday is seen as a test of whether vibrant Web activism can translate into street action.
Organisers have called for a "day of revolution against torture, poverty, corruption and unemployment".
"Activists said they wanted to use this particular day to highlight the irony of celebrating Egypt's police at a time when police brutality is making headlines," Rawya Rageh, Al Jazeera's correspondent in Cairo, said.
"In fact, the call originated from a Facebook page initially set up to honour a 28-year-old man from Alexandria who activists say was tortured to death by police.
"Witnesses are telling us that there are hundreds on the streets. This is an indication that the protests seem so far to be larger than the usual protests that have taken place here in Egypt over the past few years."
"The security apparatus will deal firmly and decisively with any attempt to break the law," the government's director for security in the capital Cairo said in a statement released ahead of the protests.
Since Egypt bans demonstrations without prior permission, and as opposition groups say they have been denied such permits, any protesters may be detained.
Habib el-Adli, the interior minister, has issued orders to "arrest any persons expressing their views illegally".
"I tell the public that this Facebook call comes from the youth," Adli said in an interview published by the state-owned newspaper al Ahram.
"Youth street action has no impact and security is capable of deterring any acts outside the law," he said, adding that he welcomed "stationary protests held for limited periods of time" and that police would protect the protesters.
"Our protest on the 25th is the beginning of the end," wrote organisers of a Facebook group with 87,000 followers.
"It is the end of silence, acquiescence and submission to what is happening in our country. It will be the start of a new page in Egypt's history, one of activism and demanding our rights."
Rights watchdog Amnesty International has urged Egypt's authorities "to allow peaceful protests".
Protests in Egypt, the biggest Arab state and a keystone Western ally in the Middle East, tend to be poorly attended and are often quashed swiftly by the police, who prevent marching.
The banned Muslim Brotherhood, seen as having Egypt's biggest grassroots opposition network, has not called on members to take part but said some would join in a personal capacity.
Organisers have called for protesters to not display political or religious affiliations at demonstrations. The Facebook page says: "Today is for all Egyptians."
Ismail Shaa'er, Cairo's security director, said the government had sent warnings to protest organisers that they would need an interior ministry permit.
"In the absence of such permits, these demonstrations and sit-ins will be dealt with in a legal manner and those beyond the law will be arrested," he said.
Commenting on the wave of public unrest in Tunisia, Adli, the interior minister, said talk that the "Tunisian model" could work in other Arab countries was "propaganda" and had been dismissed by politicians as "intellectual immaturity".
Activists and the opposition say the interior ministry refuses to issue protest permits, citing security reasons.
"Young people are very excited, and this time there will be much more than any other time," Ahmed Maher, one of the founders of the opposition youth movement said.
"This is going to be a real test of whether online activism in Egypt can translate into real action," Al Jazeera's Rageh reported.
"Anger has been on the rise in Egypt for the past couple of years, but we have seen similar calls fizzle out. The main difference now is that these calls are coming after what happened in Tunisia, which seems to have not only inspired activists, but actually ordinary Egyptians, a dozen of whom we have seen set themselves on fire in copycat self-immolations similar to the one that had sparked the uprising in Tunisia."
Sympathisers across the world have said they plan to protest in solidarity. In Kuwait, security forces detained three Egyptians on Monday for distributing flyers for the protests, while large demonstrations have also been planned outside the Egyptian embassies in Washington, DC, and London.
Spate of suicides
The first ramifications of the Tunisian uprising on Egypt were felt last week, when several people set themselves on fire, or attempted to do so, outside parliament and the prime minister's office. Since then, there have been almost daily reports of suicide or self-immolation attempts.
They said they were trying to emulate a young vegetable seller in the town of Sidi Bouzid in Tunisia, whose self-immolation sparked the protests that eventually led to the overthrow of former Tunisian President Zine El Abedine Ben Ali.
Nearly half of Egypt's 80 million people live below, or just above, the poverty line set by the United Nations at $2 per day.
The government has played down the attempts of self-immolation, with Ahmed Nazif, the prime minister, saying the acts were driven by people's "personal issues".
On Monday, police reported at least two self-immolation attempts in two provinces. In Cairo, a man in his 60s slashed his wrists in the middle of a small demonstration. None of three people died.