OSLO (AFP) - Several countries remain hesitant about whether to attend the Nobel Peace Prize ceremony next month, the Nobel Institute said Monday, after Beijing sent out warnings against honouring this year's laureate, Chinese dissident Liu Xiaobo.

"Several (ambassadors) have asked us to push back the deadline" for responding to the invitation to the Nobel ceremony in Oslo on December 10, Nobel Institute director Geir Lundestad told AFP.

As each year, the Institute has invited all Oslo-based ambassadors to attend the ceremony, and the diplomats had until November 15 to say whether or not they would come.

"Some are still waiting for instructions from authorities in their home countries," Lundestad said, refusing to reveal which countries were still hesitating.

The list of participants should be clearer by Thursday, he said, adding however that the final list might not be made public.

Liu, who was sentenced to 11 years in prison last December on subversion charges after co-authoring a manifesto calling for political reform in China, was announced as the winner of the Nobel Peace Prize on October 8 -- enraging China's rulers.

Beijing, which considers Liu a "criminal," has threatened there will be "consequences" for countries that support the dissident.

The Chinese embassy in Oslo sent a letter to other countries' missions in the city requesting that they refrain from attending the ceremony.

Despite the warning, most Western countries, including the United States, Britain, France and Germany have already said they will attend.

With Liu in prison and his wife Liu Xia under house arrest and his two brothers not sure of being able to leave China, there is a risk that 2010 will mark the first time in the Nobel Prize's 109-year-history that neither the laureate nor a representative will show up at the ceremony to receive the award.