BEIJING—A ceremony Friday to mark the award of the Nobel Peace Prize to Liu Xiaobo, a jailed Chinese dissident, is turning into a global showdown.

China is preventing Mr. Liu, his family and friends from attending the ceremony in Oslo, making it the first time there will be no one at the ceremony to accept the award since 1936, when it went to Carl von Ossietsky, a German journalist held in a concentration camp by Nazi Germany.

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