"Look at what Gaddafi's militias did to me," Eman al-Obaidi screamed with tears in her eyes, pulling up her coat to show blood on her upper leg.
After being intimidated by security men and hotel staff, who also beat journalists trying to interview her in the restaurant of the hotel, she was bundled into a car and driven away.
Obaidi said she had been arrested at a checkpoint in Tripoli because she was from the city of Benghazi, bastion of the insurgency against Libyan leader Muammar Gaddafi's rule.
Obaidi, who appeared to be in her 30s and was wearing a loose black coat, slippers and a scarf, said she had been raped by 15 men and held for two days. Her face was badly bruised.
"They swore at me and they filmed me. I was alone. There was whisky. I was tied up," she said, weeping and stretching out her arms to show the scars.
"They peed on me. They violated my honor."
Her story could not be independently verified. It was unclear whether she had escaped or had been released.
The government said it was treating her case as a criminal one.
"I assure you she is secure. All legal help is being offered to her," said government spokesman Mussa Ibrahim. "So far, nothing of what she says is political. It's a criminal case. It's being investigated to the full course of the law."
Earlier, officials had suggested they thought she was either drunk or mentally ill.
"LOOK AT MY FACE"
As Obaidi spoke to reporters, sobbing and shaking, hotel staff and plainclothes security men tried to push and intimidate her as she ran from one table to another, crying.
"I am not scared of anything. I will be locked up immediately after this," Obaidi shouted through her tears. "Look at my face. Look at my back. All of my body is bruised."
In the ensuing scuffle, one member of the hotel staff grabbed a knife from a table and yelled: "You traitor! How dare you say that?"
A man in civilian clothes took out a gun.
Several journalists tried to protect Obaidi, but a foreign journalist who was trying to get away from the scene with a camera on which he had recorded the scuffle was thrown to the ground and kicked.
One Western television crew had their camera smashed.
Obaidi was eventually forced into a garden outside the hotel. Journalists trying to get to her were pushed away.
"Leave me alone," she shouted at security men. One man tried to cover her mouth with his hand.
She was then dragged to a parking lot and bundled into a white car. Security men said they were taking her to hospital.
"They are taking me to jail," she yelled, struggling with the security guards. "They are taking me to jail."
Tripoli is Gaddafi's biggest stronghold, full of loyal militiamen who crack down on any form of dissent as his troops battle rebel forces in other parts of the country.
International human rights groups say Gaddafi loyalists have been arresting thousands of people. Libyan officials say they only arrest people linked to armed gangs or al Qaeda militants.
But as Western powers press on with air raids which they say are designed to protect civilians against Gaddafi's forces, people in the capital have become more outspoken in their criticism of the state.
Foreign journalists in Tripoli are unable to report freely and not allowed to leave the hotel without government escorts.
(Writing by Maria Golovnina; Editing by Kevin Liffey)