An Egyptian human rights group said on Friday an activist had been abducted by members of the security forces in plain clothes but that he had been freed later.
In a statement, the Cairo Institute for Human Rights Studies (CIHRS) said Amr Salah was seized outside his home on Thursday, citing an eyewitness saying he was beaten by four men in civilian clothes who put him into a vehicle with darkened windows.
The men identified themselves to the eyewitness as members of Egypt's security services, the statement said.
Ragab Saad Taha, a program officer at CIHRS, later told Al-Masry Al-Youm that Salah had contacted his mother by telephone on Friday to say he was released and that he was heading to his home in the coastal city of Alexandria.
Interior Ministry officials could not immediately be reached for comment.
"The incident is especially worrying because other Egyptian activists have been forcibly disappeared in the past under similar circumstances," the group said in its statement, adding that Salah was a rights activist and researcher.
Taha said that the abducted activist had previously participated in the pro-ElBaradei’s campaign to press for political reforms in Egypt.
Two policemen went on trial in July charged with the illegal arrest and torture of anti-corruption activist Khaled Said who died in their custody, a case that has provoked protests at home and abroad.
That case has become a rallying point for Egyptians who say security forces act with impunity under an emergency law allowing indefinite detention and curbs on anti-government activity. The government says the emergency law is aimed at dealing with drug and terrorism cases.