A West Bank bike trip of some 400 Palestinians, Israelis and foreigners was cut short at an Israeli military checkpoint, just moments after it began, participants said Saturday. Police officials were not available for comment, despite repeated telephone messages. The military referred all questions about the incident to the police. The bicycle tour, organized by the local chapter of the Young Men's Christian Association, or YMCA, was meant as a peaceful protest against Israeli occupation of the West Bank and in particular the army's system of checkpoints, said organizer Khader Abu Abbara. An Israeli rider, Haggai Mattar, 23, said he spoke to soldiers and police in Hebrew, and was given a variety of reasons for why the ride was being halted, including that the bikers had no permit for the tour and that there was concern about their safety. "Everyone gave a different answer," he said. A dozen riders reached Jericho by alternate roads, Abu Abbara said.