BEIJING (REUTERS).- Chinese police have prevented artist Ai Weiwei from traveling to South Korea, he said on Friday, linking it to a crackdown on dissidents ahead of the formal awarding of the Nobel Peace Prize to a prominent rights activist. Ai had been due to board a flight from Beijing to South Korea on Thursday evening, when police presented him with a piece of paper saying he was not allowed to leave China on grounds of endangering security. “They said my leaving the country would threaten national security. They were very polite, and said that in accordance with the law, I could not leave … It’s really silly,” Ai told Reuters by telephone. “I think there’s a direct connection with next week’s Nobel Peace Prize award,” he added. “The Chinese government is very upset about this.” Chinese police could not immediately be reached for comment. This year’s prize to jailed Chinese dissident Liu Xiaobo is due to be formally awarded next Friday in Norway’s capital Oslo. China, fur