Reporters Without Borders (Reporters San Frontieres - RSF) said in a statement on Friday it "strongly condemned the use of violence to intimidate journalists" and called on the Egyptian authorities to investigate the attack swiftly.
Abd al-Halim Qandil, editor of al-Arabi newspaper, has in the past criticised the idea of inherited power, amid talk Egyptian President Husni Mubarak may be grooming his son as a future leader, although officials deny any such plans.
Egyptian officials say the press enjoys freedom of speech and opposition newspapers often criticise the cabinet and its policies. But many journalists say they practise a degree of self-censorship on matters related to the presidency.
Qandil told RSF he was bundled into a car by assailants early on 2 November after attending a pre-dawn meal during the Muslim fasting month of Ramadan.
Gamal Mubarak's rising political
profile is a sensitive media issue
He said he was beaten by his attackers and repeatedly told: "You have to stop talking about people in high places."
The RSF statement said: "This kind of crude and violent intimidation of journalists should have no place in Egypt. The authorities' obligation to react firmly to such threats is all the greater since it involves a journalist known as a fierce critic of the government and of President Husni Mubarak."
Qandil has reported the attack to the public prosecutor. A judicial source earlier said Qandil had accused the interior ministry of involvement in the attack. The ministry has denied any knowledge of the incident.