BEIJING, December 10, 2010 (AFP) - At least 100 people protested outside the United Nations office in Beijing Friday, Human Rights Day, UN employees said, as the Nobel committee prepared to honour peace laureate Liu Xiaobo in Oslo.

"We saw a large group of people in front of the compound and it was larger than in previous years on Human Rights Day," one official, who refused to be named, told AFP.

The official could not give details as to how big the crowd was or what they were protesting about.

But another employee who asked not to be identified told AFP between 100 and 200 people had demonstrated.

More than a dozen security vehicles were stationed outside the complex in the city centre and police were asking passers-by for proof of identity, an AFP correspondent said.

A ceremony in Liu's honour is due to take place later Friday in Oslo, but neither Liu, who is serving an 11-year prison sentence, his wife -- under house arrest -- nor other members of his family will be able to collect his award.

Beijing has clamped down on dissidents, the Internet and the media ahead of the ceremony, with activists missing and strong security at his wife's flat.

Liu was jailed in December last year on subversion charges after he co-authored Charter 08, a petition calling for political reform in one-party China.

December 10 is international Human Rights Day, marking the adoption in 1948 by the UN General Assembly of the Universal Declaration of Human Rights.