Updated at 11 a.m. ET

An Egyptian-American columnist and activist told msnbc.com Thursday that she was sexually assaulted and beaten by police after being arrested in Cairo.

Speaking after her release following hours of questioning, Mona Eltahawy said her right hand and left arm were broken on Wednesday night by riot police who dragged her by the hair and groped her between the legs.

"They acted like animals," she told msnbc.com in a telephone interview. "I was filming the protests with my camera phone on Mohammed Mahmoud Street when they surrounded me and pulled me away."

Eltahawy posted on her Twitter account that her right hand was "so swollen I can't close it."

She posted a picture of her hand and tweeted that she was being taken to hospital.

She alleged at least one officer stuck his hand down her jeans, adding: "I managed to stop him before he touched my genitals. They touched me all over, groped every part of my body and called me names, called me a whore."

The claims by the Egyptian-born activist, who holds dual citizenship, could not immediately be verified.

She told msnbc.com she had been held for several hours being questioned by the Interior Ministry and Military Intelligence officials before being released early on Thursday.

"I think when they realised I had dual citizenship they were aware they had to be more careful," she said. "Eventually they apologized for the police behaviour and sent me home in a taxi."

"They even gave me 50 [Egyptian] pounds for the fare. The journey was only 18 pounds but I gave the driver the whole lot because I just wanted nothing to do with their money," she added.

Earlier she had posted on Twitter: "The dogs of the CSF (Central Security Force) subjected me to the worst sexual assault ever."

The latest news on protests in Egypt

According to her blog, Eltahawy spoke in May at the Oslo Freedom Forum about the power of censorship.

Camera seized
An American filmmaker and journalist, Jehane Nojaim, was also arrested by Egyptian police while documenting clashes in Tahrir Square, she told a colleague, Karim Amer, by phone.

Nojaim is an award-winning filmmaker of Egyptian ancestry who is best-known for her Al-Jazeera TV documentary "Control Room."

Amer said Nojaim was detained and her camera was confiscated. Amer said he was separated from her after they both fled from tear gas being fired by authorities.

The U.S. Department of State tweeted early Thursday that it was aware of the reports that Nojaim and Elthawy had been arrested and said the U.S. Embassy in Cairo was "engaging authorities." 

By Ian Johnston and Alastair Jamieson at msnbc.com, NBC news and the Associated Press