BEIJING — One Chinese activist died after the authorities ignored pleas to treat her liver disease while she was in detention. Another was left with years of chronic pain after prison doctors misdiagnosed a problem with his pancreas.

Accusations that Liu Xiaobo, the imprisoned Nobel Peace laureate who has late-stage liver cancer, has not received proper treatment have brought new scrutiny to what human rights advocates say is a pattern in Chinese prisons: the denial of health care to dissidents to intimidate and punish them.

At some prisons, requests for health checkups and medicine are refused, human rights experts and former prisoners say. At others, ill prisoners suffer physical abuse and malnutrition. In some cases, chronic ailments and serious diseases are left untreated, or medical care is repeatedly delayed.

“There is a real fear amongst prisoners of conscience and their families that authorities aren’t afraid to let them die from lack of adequate medical care,” said Frances Eve, a researcher at Chinese Human Rights Defenders, a coalition of advocates.