Freelance journalist Jesse Rosenfeld says police beat him Saturday night in Toronto as he covered a G20 demonstration.

A second journalist who witnessed the incident said it was "not a great night for democracy."

Steve Paikin, host of TVO's The Agenda public affairs show, was watching protesters on a downtown Toronto street, the Esplanade, on Saturday night.

In a message posted on Twitter, Paikin wrote that the demonstration was peaceful. "It was like an old sit-in. No one was aggressive, and yet riot squad officers moved in."

Police told him to leave, and "as I was escorted away from the demonstration, I saw two officers hold a journalist."

"The journalist identified himself as working for the Guardian," Paikin tweeted. "He talked too much and pissed the police off. Two officers held him. A third punched him in the stomach. Totally unnecessary. The man collapsed. Then the third officer drove his elbow into the man's back."

The man was Rosenfeld, 26, is a freelancer from Toronto who is now based in the Middle East. He writes for Now Magazine, The Washington Report on Middle East Affairs, The Montreal Mirror and This Magazine.

"An officer came up to me, looked at my ID, my alternative media centre press pass and said: 'This isn't a legitimate press pass. Put him under arrest!'" Rosenfeld said.

"At which point I was immediately jumped and beaten. The officer grabbed my arm, ripped it behind my back. I was punched in the stomach to make me go down to the ground. I was being hit in the ribs.

"All the time I was saying 'I am not resisting arrest. I am a journalist. Why are you beating me?'"

According to Paikin, "this guy is about 5-foot-4, 140 pounds. I later spoke to his father and found out he's only got one kidney, and he's an asthmatic. Hard to see how he was a threat to anything."

"Not a great night for democracy in our city, the way I saw it."

Toronto police said Rosenfeld is welcome to file a complaint. He has hired a lawyer.

Rosenfeld was not the only person whose arrest perturbed Paikin.

On Sunday, he said he had heard from author and academic Valerie Zawilski. She had just been released from jail after being arrested for breaching peace during the Saturday night demonstration. "Gimme a break," Paikin tweeted.

And Paikin monitored the arrest of the son of Kate Holloway. Holloway is a journalist, activist and was a Liberal party candidate in the 2007 Ontario election.

Her son Sam and Sam's girlfriend were watching a demonstration Saturday night and were arrested.

They spent a night in jail and Sam's parents had no idea where they were.

With files from the CBC's Dave Seglins