LONDON — A gathering of Nobel Peace Prize laureates opened in Rome on Friday, overshadowed by a dispute with the Vatican over reports that Pope Francis had refused to grant an audience to the Dalai Lama, the 1989 laureate, for fear of offending China.

The pope’s action, reported by news agencies and by the Dalai Lama’s followers, seemed to represent a further success for China in its efforts to isolate the exiled Tibetan spiritual leader, who is regarded as one of Beijing’s principal political nemeses.

The laureates’ gathering was initially set to take place in Cape Town in October, but the South African government of President Jacob G. Zuma, which has close economic ties with China, refused to grant the 79-year-old Dalai Lama a visa.

The action provoked a boycott by other Nobel laureates. Archbishop Desmond M. Tutu, the South African winner of the 1984 prize for his battle against apartheid, responded to Mr. Zuma’s action by saying he was “ashamed to call this lickspittle bunch my government.”