And last week, when a State Department official requested a meeting with Ms. Lin, to discuss the continuing harassment of her father in China, pageant executives refused to let her go, a State Department official said. They relented only after Ms. Lin agreed to be accompanied by a pageant employee, who insisted on attending the meeting. The chaperone later turned down a State Department request to post a photo of the meeting on Twitter.

Jacob Wallenberg, a friend who has spoken to Ms. Lin by phone, said pageant employees warned her that she would be ejected from the competition if she spoke to reporters. “They have specifically told her not to talk about human rights during the pageant, even though that is her official platform,” he said. “She is very frustrated.”

The Miss World organization declined to answer questions about the restrictions it has placed on Ms. Lin, but friends say they have little doubt about its motivations: Pageant officials, they said, are simply doing the bidding of the Chinese government, which has spent the past year trying to silence Ms. Lin, who was born in China but emigrated to Canada at 13.

Since 2003, the Miss World pageant has been held six times in Sanya, a tropical city in southern China, and Chinese companies have become the main sponsors of the decades-old competition. The local government has spent $31 million to upgrade infrastructure for the competition, according to the Chinese media.

Last year, after the Chinese authorities refused to issue Ms. Lin a visa to attend the finals, she flew to Hong Kong, hoping to obtain a visa at the border. She was turned away, and her photo disappeared from the pageant’s official website. “Why is a powerful country like China so afraid of a beauty queen?” she said at the time.