A police officer said Bahu Bakhsh and Marwa Faruk, both women, and Ibrahim al-Sahari were handing out leaflets on Friday calling for a 4 February rally at Cairo's International Book Fair that would express opposition to Mubarak's re-election or the prospect of his son Gamal succeeding him.
Public opposition to Mubarak's standing in the September polls has been mounting, but this is the first time police have arrested people involved in the campaign. Earlier this month, about 100 people demonstrated against another Mubarak presidential term in Cairo and last month about 1000 people held a similar protest.
Lawyer Ahmad Saif said state security prosecutors questioned the three detainees in the evening and would continue to interrogate them on Saturday.
Undermining general security
The police officer said the detainees are accused of possession, publication and distribution of leaflets that undermine general security.
Saif Said al-Sahari, 30, a journalist with the financial paper al-Alam al-Yum, had told him on the phone that police assaulted him during his arrest.
There is speculation that Gamal
is going to succeed his father
The three activists are members of the Socialist Studies Centre, an independent organisation in Cairo that publishes books and holds seminars on socialism.
President Mubarak, 76, has been in power since 1981. He has never appointed a vice-president and there is widespread speculation that Gamal is being groomed to succeed him.
Both Mubaraks have denied this, but Gamal has said he cannot stop others from nominating him for the presidency. Earlier this month a cabinet minister said the president would stand again this year.
Presidential elections are essentially a referendum in which people vote "yes" or "no" for a single candidate approved by the parliament. The parliament has been dominated by the ruling party since political parties were revived in the 1970s.
Meanwhile, police clashed on Friday with about 500 demonstrators who were protesting in Sinai over the three-month detention of people suspected of involvement in last year's attacks in the peninsula, a police officer and a lawyer said.
Police arrested three protesters, and three police officers and about 10 demonstrators were injured in the clashes outside the municipal offices in the north Sinai town of al-Arish, lawyer Khalid Ali said in a phone call.
Fighters killed 34 people in the
Sinai bombings on 7 October
A police officer said police fired tear gas after protesters hurled stones. Five demonstrators and one policeman were treated in hospital, the officer said.
The demonstration began as a protest march, mostly by women angry at the prolonged detention of their loved ones. They walked from al-Arish's main mosque after Friday prayers to the town hall.
Lawyer Ali said prosecutors questioned the three detained men on Friday and would continue interrogating them on Saturday.
On 7 October, a series of bombs were detonated in the Sinai resorts of Taba and Ras Shitan, killing 34 people. One of the bombs destroyed a wing of the Taba Hilton Hotel.
The alleged Palestinian mastermind of the attacks, who died in the blasts, and five Egyptian suspects came from al-Arish, 270km northeast of Cairo, the government said.