Google Inc. executive Wael Ghonim who had gone missing in Cairo for more than a week was released on Monday and was joining the anti0Mubarak protest in Tahrir Square, Al Arabiya reported.
Ghonim said he was kept blindfolded for two weeks while being detained by Egyptian state security.
Google said last week that Ghonim, the firm's head of marketing for the Middle East and North Africa, had not been seen since Jan. 27, two days after anti-government protests erupted in Egypt.
Ghonim said after his release that he was picked up by three plainclothes men in a street in Cairo, bundled into a car and taken off for interrogation by state security men.
"I am not terrorist or drug-dealer"
He said he was blindfolded throughout his detention, according to Reuters.
"I am not a symbol or a hero or anything like that, but what happened to me is a crime," he told reporters.
"If you want to arrest me, that's your right. But there are laws and I am not a terrorist or a drug-dealer. We have to tear down this system based on not being able to speak out."
Activists said Ghonim had been involved in founding "We are all Khaled Said", an anti-torture Facebook group named after an activist who rights groups said was beaten to death by police in the port city of Alexandria. Two officers now face trial.
That Facebook group has been credited with sparking a public outcry over police torture and helping inspire the protests demanding an end to President Hosni Mubarak's 30 year rule.
Ghonim said he was not allowed any news on the protests nor was his family informed of his detention.
He said new Interior Minister Mahmoud Wagdy told him that the anti-government protests had taken the ruling party by surprise.
"The (interior) minister said 'I've only been minister for seven days. You have achieved gains, and no one expected that. How did you do all that? All of us, those inside the party, inside the political system, were amazed, taken by surprise.'"
Ghonim said Wagdy added: "We couldn't understand what was happening. Now the situation is over. We won't go back again."
Google had launched a service to help Egyptians use Twitter despite government Internet restrictions by dialing a telephone number and leaving a voice mail that would then be sent on the online service.
Egyptian telecoms tycoon Naguib Sawiris had said earlier that authorities promised him that Ghonim would be freed later Monday.
Sawiris told a television satellite channel he owns that he had asked for Wael Ghonim's release during talks with Vice President Omar Suleiman on Sunday, alongside opposition groups, to try to end the country's political turmoil.
Google began a public search for Ghonim last week, giving out a telephone number for information about him.
On Jan. 27, Ghonim was apparently circumventing a government shutdown of the Internet - a post on a Twitter account listed under his name said: "Very worried as it seems that government is planning a war crime tomorrow against people. We are all ready to die." Ghonim showed solidarity with protesters rallying against President Hosni Mubarak.
A YouTube video of a street protest shows the detention of a man resembling Ghonim. In the footage, men in plainclothes approach a line of protesters and grab the man identified as Ghonim, hustling him through a gap in a squad of riot police.
Google launched a service for Egypt to allow people to dial a telephone number and leave a voice mail which would then be sent on Twitter and could be heard on telephones to try to work around Internet restrictions imposed by the government when the protests gathered pace.