In the West Bank city of Ramallah, about 200 activists from various opposition groups had gathered in a meeting hall to issue a declaration opposing the peace talks when dozens of young men sitting in the audience stood up, hoisted posters of Abbas and shouted slogans in support of the Palestinian leader.

The meeting quickly broke up in a confused scene of shouting and finger-pointing, without any resolution being approved.

One of the organizers, independent lawmaker Mustafa Barghouti, and activists from other factions said the young age of the men, the well-organized nature of the protest and the fact that uniformed policemen were waiting outside to question activists showed the men were security officers.

The crackdown was a stark violation of human rights by the Palestinian Authority, Barghouti said.

Adnan Damiri, a spokesman for the Palestinian security forces, denied the charge, but the official Palestinian news agency WAFA said Abbas has ordered an investigation into the incident.

One leading human rights group, Al-Haq, said police grabbed one of its members and confiscated his camera and injured another who came to his aid.