Those who have not been turned back are held at detention centers run by private contractors on nearby islands, including the tiny nation of Nauru. A report this week by an Australian Senate committee portrayed the Nauru center as a purgatory where children are sexually abused, guards give detainees marijuana in exchange for sex and some asylum seekers are so desperate that they stitch their lips shut in an act of protest. Instead of stopping the abuses, the Australian government has sought to hide them from the world.

Image Rohingya refugees on a boat off the coast of Indonesia in May. Credit... Januar/Agence France-Presse — Getty Images

The Border Force Act, which took effect July 1, makes it a crime punishable by a two-year prison sentence for employees at detention camps to discuss the conditions there publicly. Australia and Nauru, which depends heavily on Australian foreign aid, have gone to great lengths to keep international journalists from gaining access to the detention center, in which more than 2,200 people have been held since 2012. Last year, Nauru raised the fee it charges for journalists’ visas from $200 to roughly $8,000; applicants who are turned down are not given refunds.

Scores of people who have worked at the camp have become whistle-blowers. More than 40, including medical personnel and social workers, wrote a public letter to senior government officials in July saying they would rather risk arrest than stay quiet. “If we witness child abuse in Australia we are legally obliged to report it to child protection authorities,” they wrote. “If we witness child abuse in detention centers, we can go to prison for attempting to advocate for them effectively.”

European officials have traveled to Australia on fact-finding missions recently. Mr. Abbott, who argues that aggressively intercepting the boats saves lives, has urged European governments to follow his model, and some European leaders seem so inclined.

“The Australian model may seem attractive to politicians,” said Leonard Doyle, a spokesman for the International Organization for Migration. “Politicians love fences, but what fences do is create a market for smugglers and major humanitarian problems.”